Sunday, January 11, 2009

Player Improvement By Class Year

I'm going to go in an opposite direction today from the past couple posts. In those, I looked solely at a team's performance. Today, let's look solely at individuals, and specifically, how they progress and develop as they age.

The best advanced stat I've seen that encapsulates a player's overall value would be PER - player efficiency rating. It was developed a few years ago by John Hollinger, who now does a lot of work for evaluating pro basketball. It was created by him to properly weigh offensive statistics - shooting percentage, turnovers - that typically get lost in the shuffle by just looking at points per game. It does take into account steals and blocks, but primarily, it reflects a player's offensive contributions. For more on PER, click here. It is also kept for college games now, in contrast to when I had to compile and calculate by hand the numbers I used for a primitive site a couple years ago. Click here if you want to read some juvenile writing by me about some bad Rhody teams (and apologies about the screwy formatting).

With that all in mind, let's try to answer a seemingly simple question - How much do players improve from their freshman year to their senior year? And, if we can, can we find a pattern among players that improve?

As far as methodology goes, I looked at the class that started as freshmen for the 2004-2005 college season. To qualify for a year, a player had to play at least 10 games and at least 10 minutes per game. It's fairly low threshold, but it still produces a pretty significant quantity of players - 64 freshmen in 2004-05, 86 sophomores in 2005-06, 111 juniors in 2006-07 and 109 seniors in 2007-08. The PERs by year:

Freshmen - 16.32
Sophomore - 19.17 (14.87 percent)
Junior - 20.71 (7.44 percent)
Senior - 21.58 (4.03 percent)
Total cumulative change - 5.26 (24.37 percent)
Average NCAA player - 19.85 PER

Essentially, the data means that an AVERAGE college player will improve by 1/4 from his freshmen to senior year, as long as he's good enough to get 10 minutes per game in his freshmen year.

But the distribution of this improvement is important. While there are obviously going to be exceptions and outliers, the most improvement takes place from freshmen to sophomore year. The total improvement - almost three points of value - is more than the improvement from sophomore to senior year combined. Meaning, if you aren't a star in your freshman year, you probably aren't going to be one in your senior year either.

There have to be exceptions to this though, right? Let's take a closer look at the data, maybe at some guys who were awful as freshmen. Here are the 15 players with the lowest freshmen PER, and what they ended up with as seniors:

Parfait Bitee - Rhode Island - 7.5 - 18.6
Derrick Low - Washington State - 8.5 - 19.6
Joe Crawford - Kentucky - 8.6 - 19.5
Drew Neitzel - Michigan State - 8.8 - 21.1
Marshall Brown - Missouri - 10.2 - 13.4
Jamar Butler - Ohio State - 10.3 - 21.1
Jonathan Wallace - Georgetown - 10.3 - 19.1
Kyle Weaver - Washington State - 10.4 - 22.8
Jason Rich - Florida State - 11 - 14.8
Jeremis Smith - Georgia Tech - 11.3 - 22.2
Steven Hill - Arkansas - 11.4 - 17.7
Russell Robinson - Kansas - 11.5 - 17.1
Charron Fisher - Niagara - 11.5 - 26.9
Gavin Grant - North Carolina State - 11.8 - 20.3
Dominique Kirk - Texas A&M - 11.8 - 15.2

So, this obviously proves that players only improve by 24 percent from freshmen to senior year... Except it doesn't at all. Actually, for this group of four-year players, they seem to improve by a whopping 9.27 points, or about 46.45 percent. What's going on?

Part of the problem stems from selection bias. If you're playing regular minutes as a freshman, it normally means you show at least some promise. Also, players that are too bad to get regular minutes as a freshmen will instead become part of the study as a sophomore. Or as the numbers by academic year shows, juniors and seniors.

Let's refine our numbers a bit then, and look at just players who play significant minutes for all four years of their collegiate career. How do they fare in this study?

Freshmen PER: 16.32
Senior PER: 21.7

Hey, isn't that number eerily similar? That's right - If you look at the group of 60 players who played all four years in college, as a whole their improvement is about 25 percent. Yet the bottom 15 players, the bottom quarter, improve by a substantial margin.

One issue is that it's much easier to improve from a barely-playable freshman, or a freshman on a horrible team, to an elite level player. Of the 15 worst, none improved to an All-American level. The biggest gainer, Charron Fisher, played for Niagara, and most of his rating is tied up in his ability to create shots. He played a ton of average minutes offensively, which does have value (think Antoine Walker), but isn't something any team shoots for ideally.

So instead, let's breakdown players into ranges by 1) what they started at in PER as a freshman and 2) what they finished at as a senior.

Starting PER - Ending PER average
7.0 to 11.9 - 19.29 (15 players)
12.0 to 16.9 - 20.46 (22 players)
17.0 to 21.9 - 24.33 (18 players)
22.0 to 27.3 - 24.2 (6 players)

Once you break players up into ranges, the results become a little more clear - it's incredibly hard for a player to break through the ceiling of a 24 PER. Once you hit this level, it's harder to improve. Then again, most of the players putting up 22+ PERs as freshmen don't need to improve their games to become viable contributors. D.J. White (26.3), Chris Lofton (23.0) and Bryant Dunston (24.9) were very good from the start of their careers.

Some interesting numbers pop out when you look for analomies. The player to improve the most from freshman to senior was Georgetown center Roy Hibbert, from 15.2 to 31.1. Arizona's Jawaan McClellan (-4.9) and Houston's Lanny Smith (-4.8) regressed the most; both started in the mid-16s.

Let me try to bring it all home and summarize after looking at this group of players...

- In a proclaimation sure to make Dickie V. unhappy, if you're an elite player as a freshmen, there isn't any evidence to suggest that you're "helped" from extra years at school. Players posting PERs greater than 20, on average, didn't see significant gains by staying in school four years.

- If you're good enough to get 10 minutes per game as a freshmen, it suggests you'll be decent enough to be a solid regular three years later, even if you start out horribly. From personal observation, Parfait Bitee was about as bad as you could be as a freshman guard (PER 7.5), but he was a solid starter (18.6) by his senior year.

- ... But if your PER is too low as a freshman, it suggest superstardom isn't in your future. The lowest starting PER (15.9) that eventually ended up with a PER greater than 30 is Roy Hibbert. Most players that are eventually great start out as very good.

These are my preliminary findings, and I'll take a look at some other years in a future entry, to see if the trend holds for some other classes. Feel free to post suggestions, comments and questions.

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