Let's start here:
Gorgui Dieng's stats per 100 possessions.
Gorgui Dieng's advanced stats for the season.
Data courtesy of Basketball-Reference
The Timberwolves drafted Gorgui Dieng from Louisville with the 21st pick in the 2013 draft, viewing him as a project big man who might be able to help the team defensively. He was a good college player who helped his team to a national championship and was widely viewed as a very high character person (he is still venerated in Louisville). The clear downside was that he would be 24 years old as a rookie.
He struggled to get into the rotation in the early part of the season, largely because the Wolves had Nikola Pekovic and Ronny Turiaf in front of him playing well. Eventually injuries gave him some chances, but early on he was so foul prone that he couldn't stay on the floor. (In the games he played before the new year, he averaged roughly a foul every four minutes).
His final 18 games of the season, however, were so impressive that he made 2nd team All-Rookie (albeit in a very weak rookie class) despite playing only 818 minutes for the entire season. Here are some stats from those 18 games (15 of them starts):
Averaging a double-double while shooting 53% in 30 minutes a game is nothing to sneeze at. You will also see that he only committed a foul roughly every 10 minutes during this stretch as he learned how to play and what he could and couldn't get away with. It was a clear step forward for him when he got the opportunity to play extended minutes with the starters. He shot the ball much better from the field during this stretch than he did during the earlier part of the season (42.6% prior to this stretch) and from the free throw line (44% prior to this stretch).
So who is Gorgui Dieng as a player? The advanced stats are mixed on him: Win Shares likes him quite a bit, the advanced plus/minus stats like his defense OK, but see his offense as a train wreck. His defensive numbers via Synergy paint a picture of someone pretty over matched, but do not capture team defensive effects.
Is Dieng a potential starting center? Is he someone who can replace the much more expensive Nikola Pekovic? Is he a better fit? Is he best suited as a limited minutes back up? Where does he need to improve? Are those improvements likely? Possible?
Those are the questions I want to try to answer in this article.
One of the problems with trying to contextualize Dieng's play and stats is that a significant chunk of his playing time was late in blowouts, and/or while he was on the floor with the consistently wretched Wolves bench. Fortunately, we have a way of parsing his playing time to get a better look at what went on when he was on the floor with the Wovles best lineups:
|1||C. Brewer | K. Love | K. Martin | N. Pekovic | R. Rubio||1051:53||+0.5||+3.8||-.015||+0.4||-0.4||+.025||-.015||+10.3||+11.6||+.046||+11.7||+3.6||+7.4||+1.8||+7.4||+2.6||+6.1||+2.4||+1.8||-3.8||-3.2||-3.3|
|2||C. Brewer | G. Dieng | K. Love | K. Martin | R. Rubio||225:24||-5.3||-6.4||-.024||-0.2||-0.7||+.001||-.022||+10.2||+10.6||+.082||-0.7||-4.2||-10.6||-6.2||-10.6||-5.2||-11.6||+2.4||+4.0||-0.9||-3.5||-3.5|
Here we can see that the two most used Wolves lineups last season were first, their regular starting lineup, and second, their regular starting lineup with Dieng replacing Pekovic. That gives us an opportunity for some direct comparisons, with caveats. Namely, the minutes Dieng got with this lineup were not randomly distributed through the season, but rather were all at the end of the season, when the other players might have been playing better or worse (likely worse). Further, the sample size for the lineup with Dieng is rather small: only 225 total minutes. Still, it tells us something.
The main thing it tells us is that the team was much, much better with Pek than with Dieng. They were +11.7 points per 100 possessions better than opponents with Pek, (which makes that one of the strongest lineups in the league), and -0.7 points worse with Dieng. So all other things being equal, it's a mammoth 12.4 net points/100 possessions difference between the two centers. (In one of the statistical anomalies of the season, however, the team was only 27-27 in games Pekovic played and 13-15 without him).
What gives? By far the biggest, most glaring difference is rebounding. The Wolves were a positive rebounding team on both ends with Pekovic in the lineup, and a badly negative one with Dieng instead. This led to a huge difference in field goal attempts, where the Wolves were +3.8/100 with Pek, a shocking -6.4/100 with Dieng. And that accounts for essentially the entire difference in points/100 between the lineups. There are some other differences--the team gets more steals and blocks when Dieng is in the game compared to Pekovic, but those differences are swamped by the massive rebounding difference.
The question is why was the rebounding so much worse with Dieng? Gorgui was, in fact, a terrific individual rebounder as a rookie; it was one of the real positive surprises of his season. He recorded an Orb% of 13.4, a Drb% of 26.9 and a total reb% of 20. That compares favorably to Pekovic's 13.1%, 17.6% and 15.3% respectively.
There are two explanations that occur. The first is that something about Pekovic's presence allows his teammates to rebound better. The second is that by the time Dieng got his minutes with the first team, there was less effort by the other guys (particularly Kevin Love, the team's best rebounder) and this showed up in the rebounding stats.
I prefer the first explanation, though certainly they are not mutually exclusive. Pekovic's monstrous physical presence occupies opposing players on the boards so effectively that it allows other players to collect more rebounds. That sounds right to me. It's certainly true that Love's rebounding rate was down in March and April compared to previous months; that could be due to either explanation.
Let's see if Dieng's on/off court stats can shed any light:
|On − Off||MIN||21%||-.024||-0.8||-3.6||-1.8||+1.8||+0.2||+2.2||+1.8||-7.0||-.019||+3.6||+0.8||+1.8||+0.9||+0.1||-0.4||-0.1||+0.0||-.005||-4.4||-4.4||-3.6||+1.8||+0.3||+2.3||+1.8||-7.1|
And for comparison's sake, Pekovic:
|On − Off||MIN||42%||+.022||+2.6||+5.2||+3.8||+0.5||+0.3||-3.2||+0.0||+5.6||+.013||-5.2||-2.6||-3.8||+0.5||+0.0||+0.0||+0.3||-2.7||+.009||+7.8||+7.8||+7.7||+0.4||+0.3||-3.1||+0.0||+8.4|
We can see from Dieng's on/off that the Wolves were a somewhat worse rebounding team with him on the court when considering all of his minutes (48.9% total rebounding on court, 50.7% total rebounding off). But the difference pales in comparison to the difference when he is swapped in the starting lineup with Pekovic. Pekovic has a much bigger positive effect on the team's rebounding numbers over all minutes and lineups than Dieng has a negative effect. This leads me to believe that the rebounding difference in the lineup is more about Pekovic's positive impact on team rebounding than on a diminution in effort during the minutes that Dieng was playing with the other four starters.
These on court/off court numbers give us the opportunity to segue to the issue of defense.
The first thing to note is that opponent's offensive rating is the same with Dieng on the court as it is with him off the court. How they get there, however, is somewhat different. As we've seen, opponents get more offensive rebounds with Dieng on the court, but we see here that their efg% is lower. This is a key point, and the first evidence we have of a positive effect on defense.
We can drill this down somewhat using Synergy. Gorgui Dieng is a poor on the ball defender. When his man finishes a play with either a shot attempt, free throws, or a turnover, he has one of the worst defensive records in the league, giving up 1.06 points per play. That is 451st in the NBA. Compare to Pekovic, who is 148th in the league at .86 ppp.
Where he really struggles is in defending post-ups. There his man averaged 1.16 ppp, which is disastrous (Pek gave up .73 ppp in post-up situations). I watched every one of his post-up defensive plays that ended with his man shooting, getting fouled, or turning it over, and the problem was obvious even to my untrained eye. He consistently got bullied in the paint. He simply was not strong enough, and/or lacked the proper technique, to hold his ground against guys posting him up.
Time and time again players would catch the ball outside the paint, and use their strength to bully Dieng under the basket or clear space for an uncontested 5-8 footer. This is an area which he must improve upon in order to become a good defender in the NBA, and the good news is that he seems to know it. Here is a snippet of an interview he did on the Wolves website:
What are you focusing on this offseason. We talked earlier that while you're in town you're working at the U of M. What are you working on as far as on the court, off the court preparation for Year 2?
Right now I'm just working on my strength. I know I need to be stronger, and you know that's what I'm focusing on right now.
Is that something you learned from being a rookie, knowing what you might want to work on more this offseason since you've been through and NBA season and know what to expect?
Yeah, I think I learned a lot. There are a lot of plays that I couldn't finish because of my strength. There are a lot of plays I couldn't make because of my strength, and I think I need to focus more on my strength right now to get stronger and still explosive. I think if I can have those two, they will help me a lot coming into next season.
He also had bad defensive results when guarding the roll man in the pick and roll, but the sample size is very small and seems to be as much a function of tactics as anything else. It's clear that the centers were instructed to sag into the paint when their man was setting the screen, which resulted in a lot of open jumpers for opposing big men on the roll. Dieng didn't do a great job closing out on those, but in truth, it was pretty clearly a shot the team was willing to give up; in Dieng's case they just made a bunch of them.
So if he does a relatively poor job in on the ball defensive situations, and yet the team gives up a lower efg% when he is on the floor, we have to conclude that he has a positive effect on team defense--that his help defense is a positive. It's difficult to figure out the ways in which this is true using the available statistics. One thing we can look at is blocked shots. The team blocked a higher percentage of shots with Dieng in the game, and he was 2nd on the team (to Ronny Turiaf) in both block percentage and blocks per 100 possessions.
I looked at all of his blocked shots on Synergy, and they were virtually all against someone other than the man he was guarding. In other words, compared to Pekovic, he was much stronger at protecting the rim on help defense via the blocked shot. That's about as much as I can conclude definitely.
We know that the Wolves gave up the highest opponent field goal percentage in the league on shots within 5 feet, at 63.1%. They did an OK job preventing such shot attempts--15th in the league, which is actually more impressive than it sounds when you consider they played at the 4th highest pace in the NBA and rarely took away such attempts via fouls. But they were atrocious when their opponents managed to get such shots. That was consistent throughout the year; it was something I regularly tracked. They were always OK at preventing close shot attempts, but abysmal and forcing misses on those shots.
What I can't do without watching every defensive possession is determine what effect personnel had on the frequency or success of those specific shots.
However, NBA.com tracks something called "defending the rim," which they define as:
the defender being within five feet of the basket and within five feet of the offensive player attempting the shot.
Now, I have to say I'm not entirely sure how much I trust these numbers, but for what it's worth, there are 194 players who played at least 13 minutes a game and at least 40 games and "defended" at least 2 shots per game at the rim. Among these players, Dieng gave up a remarkable number of attempts given his minutes, but I'm not sure that's a bad thing. It might be that he was simply quick and active enough to get within range on more attempts than the average big man.
He gave up a 51.5% field goal percentage on those shots he defended. That was 88th among the 194 player sample, so not bad. The list makes some sense--most of the guys you would think of as quality rim protectors are in fact toward the top of the list in FG% against on this list.
Meanwhile, for comparison's sake, Nikola Pekovic really struggled here. Of the shots that he "defended" at the rim, he gave up a 55.2% on those shots, which was good for 154th out of the 194 player sample. He also "defended" far fewer attempts on a per minute basis than Dieng, which again can be interpreted in different ways.
This suggests that Dieng was an active and reasonably effective defender around the rim, certainly more so than Pekovic. On the other hand, as we saw with Synergy, he isn't nearly the post defender that Pek is. Pek does a very good job using his strength to keep his man away from the basket and force him into more difficult post shots. Dieng does seem better at providing help defense around the rim.
What all this adds up to is that, although over all of his minutes Dieng had a measurable positive effect on opponents' efg%, when we look at only the starting unit with Pekovic vs. Dieng, it was negligible negative effect (.494 with the regular starting unit, .496 with the starting unit and Dieng).
Which brings us to his offensive contributions. Pure RAPM had him at -.2.2/100, while xRAPM had him at -3.5. In other words, bad. Synergy agrees. He scored .88 ppp, which was 281st in the league. Again for comparison's sake, Pekovic scored 1.05 ppp, which was 32nd in the league. He used possessions inefficiently, but didn't use too many of them, as he carried only a 16.8% usage rate.
A big problem for Dieng was that he turned the ball over far too much. His 16.8% turnover rate was the 2nd highest on the team after Ricky Rubio, who obviously had the ball in his hands much more frequently and had a radically different job. Another problem was that he shot only 63% from the free throw line, which cost the team points.
To be fair, he improved in both of these areas, as well as field goal shooting, once he got into the regular rotation. Over the last 18 games, he went from a turnover every 13 minutes to a turnover every 17 minutes. His free throw shooting was over 70%, and his field goal shooting was nearly 53%, all significantly better than his early season numbers.
Still, he was a poor offensive player by most measures. Let's dive in a little bit with Synergy. Just as on defense, he really struggled in his offensive post-ups. .75 ppp is not good. We knew this coming in; posting up was not his game in college, and isn't in the NBA either. He lacks the strength to be effective, and his footwork and post-moves are rudimentary. He generally doesn't look comfortable with his back to the basket.
Another area where he struggles, and this came as a bit of a surprise to me, is in converting offensive rebounds. When he finishes a play off an offensive rebound, he only scores .95 ppp, which is significantly behind Pek's 1.23. I was surprised to see how many put backs he just missed.
His best offense is when he's the roll man on the pick and roll. There he scored 1.14 ppp, which was good for 26th in the league (and the Wolves have three guys who are really good at this: Pek was 13th in the league on ppp as the roller, and Love was 31st.). Somewhat counter-intuitively, at least to me, he was able to keep his turnovers manageable on these plays (9.2%, lower than his post-up turnover rate).
Let's take a look at his shot chart:
It's a small sample size everywhere but around the basket, but Dieng did show that he might be able to make 15 footers at a reasonable rate going forward. He needs to get stronger for offense as well, which might allow him to convert more of the offensive rebounds he grabs in traffic. He desperately needs to cut down on his turnovers. The Wolves should use him in pick and rolls when he's in there, but shouldn't post him up until he shows real improvement in that area.
On the whole, he was not a good offensive player. He did show improvement late in the season when playing with the starting unit, which hopefully means good things going forward. Even with those improvements, however, the team was better offensively, even ignoring rebounds, with Pekovic in there. Their efg% was .48 with Pek, .47 with Dieng. They also turned it over more with Dieng in the game. This is all to be expected and not a knock on Dieng; he was a rookie, and Pekovic is one of the better offensive centers in the NBA.
So how do we put this all together?
We have a rookie. Who was 24 years old. And yet didn't take up basketball until quite late. We have a player who showed some ability to provide help defense in the post--not at the level of the best in the game, but certainly better than the other bigs on the Wolves roster. But he also was terrible defending on the ball particularly in the post.
We have a player who was an excellent individual rebounder, but didn't help the team rebound very well. A player who looks like he can make a 15 foot jumper, but can't score in the post. A player who can convert on the pick and roll, but turns the ball over at an untenable rate.
In other words, we have a player, like all players, with a combination of strengths and weaknesses. At this point, it seems clear that he is not someone who is going to be a big asset playing starters minutes. He just has too many weaknesses, especially, well, his weakness.
In order to get to that level, he has to be better defending the post. He has a long way to go to get there, and it has to start with getting stronger. We know he's working on that this summer; hopefully he achieves some results. Added strength should also help him get better offensively, both in the post and converting offensive rebounds, where he really struggled. I don't expect him to ever be a primary or secondary offensive option like Pekovic can be; he doesn't appear to have the natural feel for offense. But making free throws consistently and cutting down on the turnovers in the post would go a long way toward making him acceptable. He started making inroads in both of those areas late in the season
If he is going to be a starting caliber player, however, it's going to be due to his defense. Right now, he's not close. Rookies often struggle defensively, so certainly there is hope. He was very effective in college, and showed the ability to provide useful help defense this year.
Dieng is in a good spot to improve his game. He plays behind a better center against whom he can work in practice. He has some different skills that can help the team now, and has the opportunity to improve in areas that will make him a better player. He's already capable of being a useful rotation player, meaning he's a success at the 21st spot in the draft.
How much he improves is an open question. Older rookies like Dieng often do not get a lot better, but on the other hand we saw measurable improvements throughout his rookie year. A couple more steps forward and Dieng becomes a very valuable player, hopefully while he's still on his rookie contract.
He's definitely a guy who it's easy to root for.