Now that Summer League is over and the summer doldrums can officially begin, I thought it would be a good time to just post some relevant stats for both first- and second-year players that were selected in the top half of the first round.
One of the things that were a popular topic during games was just how predictive advanced stats were in the first place. ESPN's Kevin Pelton took a stab at answering the question in his latest Insider piece. The answer, it turns out, is marginally useful for rookies and not really useful at all for second-year players.
However, that figure gets more interesting when it's broken down by NBA experience. Veteran players who were in the league the previous season have an even smaller correlation of .101 between 2012 summer performance (as measured by my per-minute win percentage rating) and 2012-13. Once we account for how well these players were projected to play in 2012-13, their summer-league stats have zero predictive value.
By contrast, the correlation of .463 for rookies is far higher. In fact, it's nearly as strong as the relationship between my college stat translations and rookie performance (.468). When we combine the two factors to try to predict how well players will fare as rookies, summer-league stats make up about a quarter of the combined projection.
He also adds:
Shot-blocking and defensive rebounding translate particularly well from the summer league to the regular season. That's good news for players, like Milwaukee's John Henson, who have been controlling the glass and blocking shots.
Conversely, shooting during the summer tends to be much less predictive than randomness alone would indicate. The better players shot from 3-point range during last season's summer league (minimum 20 attempts), the worse they shot come November. Accurate 2-point shooting also failed to translate, along with offensive rebounding, steals and even usage rate.
This means, as Kevin Sawyer among others have said, Summer League is usually good at weeding out who might be busts but isn't so good at predicting who will be successful. That's bad news for Trey Burke, Ben McLemore and Otto Porter in the rookie class. And with the big-man stats translating relatively smoothly, that's good news for Andre Drummond (not that Pistons fans needed any more convincing).
Summer League Rookies
Summer-League 2nd-year Players
* Detroit Pistons player