I recently wrote a short piece for Bleacher Report regarding rookie PER and what it can mean. It's probably worth glancing over before reading this long post.
That article pretty clearly spells out how important a rookie's PER can be in predicting his future success in the league. It's not that all rookies that post a 15+ PER will become stars, but rather that if a player does not hit that number there is some serious doubt as to whether he will ever turn into an exceptional pro, especially if that player is a big man.
By quickly looking at the highest PERs posted by rookies since 2002 we see that plenty of players that were very good as rookies never progressed into exemplary NBA players. But having a good PER as a rookie is a very auspicious sign. In the last ten years, almost every future star has posted a PER above 15 his rookie year. Therefore I think rookie PER can maybe best be used to weed out players who are thought to have great potential, but in reality seem unlikely to fulfill high expectations as their careers progress.
While the Bleacher Report article gives us all the general information we need to understand rookie PER, I want to spend some more time here to look at the concept more closely, and specifically to examine exceptions.
First of all, it is worth thinking about the twenty players drafted since 2002 that have made 2+ All-Star games. Most of the best players of the last ten years started by being very good from the beginning. Historically, it's been a little tougher for guards and small forwards to hit 15+ PER as rookies than the last decade would indicate. I think a 13+ PER is a better minimum number to look at for those positions. But the reality is recently the best players, even guards, have been hitting 15+ immediately.
Let's now view rookie PER with a larger historical scope. I decided to look at every player drafted since 1992 that was selected to an All-Star game. I wanted to look for exceptions: Which star big men were under 15.0 as rookies, and which guards and small forwards were under 13.0?
Here's the list of every All-Star drafted since 1992, with their rookie PER. It's long, I suggest looking at it fullscreen:
Of the 95 All-Stars, 22 players did not meet the rookie criteria of 15+ PER for big men/13+ PER for guards and small forwards. Let's look at all the exceptions, starting from the lowest rookie PER:
- Michael Redd played a grand total of 35 minutes as a rookie. The next year, his first "real" season, his PER was 20.0. It is interesting to note that Redd hardly played at all as a rookie, even though he was an experienced college player with clear talent.
- Rashard Lewis, right out of high school, played 145 minutes total as a rookie. He had a 16.5 PER the next year with regular playing time.
- Ben Wallace, one of the better undrafted players ever, played 197 minutes as a rookie. His second year he posted a mediocre 13.4 PER. Wallace slowly grew into an exceptional player, and has had a highly unusual career path.
- Andrew Bynum only played 338 minutes as an 18 year old rookie. The next year, with more playing time, his PER was 15.4.
- Allan Houston, a two time All-Star, was simply lousy as a rookie. He bounced back to have a solid 16.4 PER his second year. Overall, Houston does not stack up well statistically compared to most multiple time All-Stars.
- Mo Williams, a one time All-Star, played 774 minutes as a rookie, and was not very good in the time given to him. He had a much better second year and never looked back.
- Chris Kaman had a terrible rookie year for a future All-Star, particularly given he was a center. In reality, Kaman has hardly ever been a superior center in the league, and it is no surprise he made only one All-Star team.
- Steve Nash has had one of the strangest career paths of any truly great player in NBA history. Nash simply was not that good his first four years in the league, and he did not flash any legitimate signs of stardom until he was 26 years old. He molded himself into an All-Star, and then stunningly got increasingly better in the following years, leading to two MVP awards. His rookie PER of 10.8 is staggeringly low for an experienced college player who goes on to dominate his position in the pros.
- Richard Hamilton somewhat struggled as a rookie, but like many of the players we are listing, was a good deal better by his second year.
- Tony Parker was 19 as a rookie, and his struggles are rather understandable given his age and the cultural gap he must have initially experienced. He was much better by the playoffs, and then had a strong following season.
- Rasheed Wallace had a PER of 11.8 as a rookie, which seems very low for a big man with such natural talent. Because we are discussing Wallace, it is easy to conjecture many of his on-court problems stemmed from chemistry issues. Whatever the reasons for his struggles were, he did manage to bounce back with an 18.4 PER the following season.
- Joe Johnson has had an odd career. His PER never got above 15 until Steve Nash arrived in Phoenix in '04-05, Johnson's fourth year in the league. He then went to Atlanta and has been regarded as an All-Star ever since. He is a player whose reputation has generally exceeded his actual talent level, which is why his name on this list doesn't strike me quite as much as Nash or either of the Wallace's. Johnson's PER as a rookie was 11.8.
- Deron Williams is the third fantastic point guard on this list who had a PER below 13 as a rookie. It is quite possible point guard is the hardest position in the NBA to play well as a rookie, and Williams did not do too badly with a 12.4 PER. He had a 17.1 PER his second year.
- Dirk Nowitzki, perhaps the best player on the list not to fulfill PER expectations, had only a 12.8 PER in 958 rookie minutes. On closer inspection, it is pretty easy to see why Nowitzki struggled early - he was a skinny 20 year old German kid playing against NBA veterans in a strike shortened season. He was much better his second year, and had a 17.5 PER.
- Baron Davis fell just a tad short of a 13 PER as a rookie, and given the position he plays this is not a huge surprise, despite Davis' physical gifts and talent.
- Kenyon Martin, a power forward, had a 13.4 PER his rookie year, which is not surprising given his career path. Martin made one All-Star game and was a disappointment as a #1 overall pick.
- Jamaal Magloire was only a one time All-Star, and like Martin, his rookie PER is not a surprise at all.
- Jermaine O'Neal was drafted right out of high school and not given a legitimate opportunity his first four years in Portland. He stagnated, never playing more than 900 minutes in a season. When he finally was traded to Indiana in '00-01, he posted a 17.5 PER. His career took off from there.
- Theo Ratliff posted a perfectly decent 14.0 PER as a rookie; he made one All-Star team.
- Tom Gugliotta posted a 14.6 PER as a rookie; like Ratliff he made just one All-Star team. Both these guys are PER exceptions of little to no consequence.
- Al Horford had a PER of 14.7 as a rookie, nearly hitting 15, but not quite. I am interested in Horford's rookie PER because there are currently two other highly touted young big men, DeMarcus Cousins and Enes Kanter, who also narrowly missed 15 as rookies. There is a chance 14.5 would be a better general criteria for big men, and not 15.0. But then again maybe not. Let's see how Cousins and Kanter do in the future.
- Mehmet Okur, a one time All-Star, just narrowly missed 15; bringing him up is just a formality to complete the list of PER exceptions.
Overall, most of the 22 PER exceptions are not that surprising. Many players that failed to meet the 15+/13+ PER criteria did not get ample minutes as rookies to prove their worth, and succeeded as soon as playing time was given to them the next year. Others, like Nowitzki and Parker, were young foreigners who had to adjust to a new country. And a few, quite simply, were never that good. Being an All-Star once in the NBA does not necessarily mean being an amazing player; guys like Kaman and Magloire are clear testaments to that.
The real PER aberrations are probably Nash, Ben Wallace and Rasheed Wallace. Nowitzki's low PER is also striking, despite the extenuating circumstances, because he ends up having such an incredibly dominant career. All four of these players had surprising statistical struggles early in their career, and then went on to become stars. Allan Houston, Richard Hamilton, Joe Johnson and Deron Williams are slight surprises, but their rookie troubles are relatively more minor, easier to understand, and seemingly less significant.
In conclusion, rookie PER is very important. I do not know if it is the single most important stat we can use to predict a rookie's future success, but I can't think of anything more important. It's amazing the consistency in which future great players achieve the 15+/13+ PER criteria. Obviously there will be exceptions, but we should not count on them happening regularly.