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The Griffin Improvement Debate -- the Statistical Case

We're looking at the question of Blake Griffin's development as a player today. This is Steve Perrin's statistical analysis of Griffin's first three seasons in the league. See also John O'Connor's take of Griffin's overall game.

Joe Robbins

Blake Griffin is a polarizing figure among NBA fans. He's been selected to start for the Western Conference All Star team for two consecutive seasons, so it's clear that a significant number of fans think he's great and love his brand of high-flying basketball. But a backlash has taken hold since his rookie season, and there's a vocal minority who insist that Griffin is all flash and no substance on the basketball court -- the mantra for this group is "All he does is dunk."

At the heart of this discussion is Griffin's development as a player. As a rookie, Griffin averaged over 22 points and 12 rebounds per game, something only six players in the history of the league had accomplished before. Five of those six are in the Hall of Fame, and the sixth (Shaquille O'Neal) will be as soon as he is eligible. Griffin set a very high bar for himself as a rookie.

Griffin set a very high bar for himself as a rookie.

After such a productive rookie season, expectations for Griffin were understandably high, especially considering that to even a casual observer, it was clear that the kid had plenty of headroom. He managed to score without having a go to move or a consistent jump shot, his free throws were sub-par -- if those things improved, imagine where his scoring would go.

The overly simplistic criticism of Griffin goes something like this -- he hasn't improved in three seasons in the league; in fact, his scoring and rebounding averages have actually decreased each season he's been in the NBA. After spending two seasons in the very exclusive 20/10 club (20 points and 10 rebounds per game), in his third season, Griffin didn't reach those milestones in either category.

10-11 11-12 12-13
PPG 22.5 20.7 18.0
RPG 12.1 10.9 8.3

That criticism is overly simplistic first and foremost because it looks at points per game, but Griffin's minutes per game have decreased each season as the team around him has become better and deeper. Playing fewer minutes is indisputably a good thing as long as the team is winning, and criticizing Griffin for a 20% drop in scoring, when his playing time has been decreasing almost as much, is meaningless.

But it's also meaningless to leave the discussion there. The fact is, we can look at points per minute and rebounds per minute, and even after normalizing for the decrease in playing time, Griffin's production has decreased from season to season. This is more difficult to explain away.

Here are Griffin's key averages on a per 36 minute basis in his first three seasons, along with his shooting percentages.

10-11 11-12 12-13
P/36 21.3 20.6 20.0
FGA/36 15.9 15.4 14.9
FG% .506 .550 .538
FTA/36 8.0 7.0 5.9
FT% .642 .520 .660
TSP .549 .560 .572
A/36 3.6 3.2 4.1
R/36 11.4 10.8 9.2

In the following chart, I've taken those key stats and using his rookie season as a baseline, shown the percentage change in Griffin's performance. This isn't every stat of course -- steals and blocked shots aren't all that interesting, and there wasn't a lot of change in them anyway -- but rather the ones that I feel are germane to the conversation of Griffin's development as a player.


(Click to enlarge.)

As you can see, his scoring and rebounding have indeed decreased, even when accounting for the decrease in playing time. On the other hand, his shooting percentages are all improved versus his rookie season (in the case of his free throw percentage, after a terrible dip during his second season).

Let's deal with the scoring question first. Notice that his scoring has decreased in lockstep with a decrease in his field goal attempts. During Griffin's rookie season the Clippers' second leading scorer was Eric Gordon, who missed 26 games. After Gordon, the roster got pretty ugly. The Clippers were dependent on Griffin for offense, entirely so while Gordon was out. Since Chris Paul arrived in town, the offensive load on Griffin is simply not as heavy. He takes fewer shots, scores fewer points, and does it all with a higher level of efficiency (as evidenced by his true shooting percentage, TSP).

Furthermore, bear in mind that basketball is a team sport. As Griffin's individual scoring has gone down the last two seasons, the Clippers as a team have improved by leaps and bounds. Obviously the team is winning more, which can be attributed in large part to Paul's arrival. Specifically the offense has gone from 22nd to seventh to fourth in efficiency over the last three seasons. Again, that's largely due to Paul, but it's pretty difficult to claim that Griffin has regressed on offense when the team has improved so drastically on the offensive end.

On the chart, we see another area of improvement in addition to shooting percentages, and that's assists. Last season Griffin averaged 4.1 assists per 36 minutes, an elite number for an NBA big. Among qualified power forwards and centers, Griffin was second only to Josh Smith in assists per minute, and he led all players 6'10 or taller. (Exhibit A in why the "All he does is dunk" argument is so completely ludicrous.)

So the statistics pretty clearly indicate that Griffin has improved both in efficiency and as a playmaker in his first three seasons in the league, while his decrease in raw scoring is a non-issue given the increases in efficiency not to mention the improvements in the team overall.

But if we look at that chart again, we still see a couple of troubling stats -- stats that show decreases in the 20% to 25% range since his rookie season.

In his final season in college, Griffin led the NCAA in rebounding with 14.4 per game (rebounding is a stat that traditionally maps to the NBA better than any other). As a rookie Griffin grabbed over 12 per game, fourth best in the league; he was eighth that season in rebounds per minute. Two seasons later, his per minute rebounding has dropped almost 20% compared to his rookie season, and he was 45th in the league (and third on the Clippers) in rebounds per minute. Think of it this way -- there are 30 NBA teams and each generally plays two bigs. If Griffin was the 45th best per minute rebounder, then about three fourths of the teams in the league had not one but two better rebounders. He was the best rebounder in the nation in college, he was a monster on the glass his rookie season -- what happened?

It's definitely more difficult to explain this one away. It should be noted that during Griffin's rookie campaign, Chris Kaman missed 50 games, leaving undersized fours like Craig Smith and Ike Diogu as the team's backup bigs. It's reasonable to assume that the likes of Reggie Evans, Kenyon Martin and Lamar Odom were taking more rebounds away from Griffin than Smith and Diogu ever did. (There's some debate as to whether teammates actually cannibalize rebounds from one another in this way, but if ever there were a player that took rebounds from teammates, it's Reggie Evans.) It's also worth noting that the Clippers as a team were a slightly better rebounding team last season than they were during Griffin's rookie season -- so again, given that it's a team sport, Griffin's drop off in rebounding hasn't appeared to hurt the team significantly. I could try to make an argument that effective team rebounding may result in fewer individual rebounds -- Griffin certainly didn't do much boxing out as a rookie, and if he simply pursued every loose rebound without regard to his assignment on the box out, it might indeed mean better individual stats and worse team stats. But it would take a lot more analysis to make a convincing case.

Still, the Clippers remain a middle of the back rebounding team, particularly on the defensive boards, where they ranked 15th out of 30 NBA teams last season. There are plenty of rebounds the team is not getting, and it seems as if Griffin should be getting more than he does.

The best explanation I can offer for Griffin's drop off on the glass is one of pacing, or even self-preservation. Griffin was a madman on the court as a rookie, diving after loose balls, throwing himself into the lane wildly, going after everything. There's no question that type of effort produces results -- but it can also shorten careers. It's possible that Griffin realized, perhaps on his own or perhaps in discussion with other players, that he had to pace himself a bit more. From the standpoint of an observer, that seems to be the biggest difference in Griffin's rebounding -- he no longer goes after EVERYTHING.

If you're looking for improvement from Griffin this season, look no further than rebounding and free throw attempts

The other area of significant statistical decrease is probably explained in the same manner. Over the course of three seasons in the league, Griffin has seen an almost straight line decrease in his free throw attempts, a total drop of over 25%. As a rookie, Griffin almost never settled for jump shots -- partly because he couldn't make very many of them. In relentlessly attacking the basket as a rookie, Griffin got to the free throw line eight times per game. As with fewer field goal attempts, fewer free throws can be explained at least in part from fewer chances -- the team is better, Griffin doesn't have to have the ball as much, doesn't have to create as much. But his trips to the line have decreased at a far greater rate than his field goal attempts, indicating that there's more at play here than simple opportunity. As with rebounding, Griffin shows less aggressiveness now than he did as a rookie.

Is Griffin a better player now than he was as a rookie? Yes, I'd say he is, but your answer may depend on how you feel about efficiency versus rebounding. His level of aggressiveness, both in rebounding and in going to the basket (and consequently getting to the line) is the one area that seems to have suffered the most over the past two seasons. Some of that may be inevitable -- he may have set a pace as a rookie that was simply unrealistic to maintain over the course of a career -- but the trend line of declining rebounds and free throws clearly needs to be reversed. There's no reason that Blake Griffin should not be among the top rebounders in the league, and as his free throw percentage continues to improve, there are easy points to be had at the line if he gets there more often. If you're looking for improvement from Griffin this season, look no further than those two areas.

Be sure to read John O'Connor's take on Griffin's overall game.