Commentary

Projecting PER for the coming season

Updated: October 5, 2009, 1:24 PM ET
By John Hollinger | ESPN Insider

For the coming NBA season, I've projected the statistics for each player who played at least 500 minutes in the NBA last season (as well as a few who saw substantial playing time in Europe).

You'll see these projections on the pages that rank players by their projected PER (Player Efficiency Rating), and on their individual pages you'll see how their numbers project in the individual categories.

By this point some of you are probably wondering how I created the projections.

It's not, as some suspect, by pulling numbers out of the air. Nor was my secret yet pervasive bias against your favorite team a factor, much as commenters like to feel otherwise.

I base the projections on a tool called similarity scores.

For each player, I use as a comparison the players from the past 20 years who are the most similar, based on age, height and stats over the past three seasons. Some players will have more comparables than others, depending on how unusual they are -- guys with freak heights (Zydrunas Ilgauskas, Nate Robinson), freak ages (Shaquille O'Neal) or freak stats (Andrei Kirilenko) will have relatively few, while a more generic player like Al Harrington or Devin Brown could have over a hundred.

From that point, I see what their most similar players did a year later, and project those changes onto the stats of the player being studied. So, for example, the reason that Andrew Bynum's PER is projected to rise sharply this year is because the most similar players also saw their PERs increase sharply at the same age; similarly, Jason Terry is expected to tank because a number of similar players hit the wall at his age.

Of course, any number of other factors can be relevant to a player's performance -- how hard he trains, for instance, and injuries, coaching, and so on. But consider these numbers a median estimate for what the player might be likely to do this coming season, other things being equal. And then, if other things aren't equal, apply your own logic from there.

John Hollinger writes for ESPN Insider. To e-mail him, click here.