It's about that time of year; football is entering mid-season, baseball is wrapping up, lattes are being Pumpkin Spiced and the NBA is finally about to start. That also means that numbers guys are crunching numbers to project the results before they happen.
Last year I did my part with a series of what I dubbed Highly Plausible Win Projections using a couple of different player metrics to estimate wins for the NBA. This year I am using an exploratory player metric I created using publicly released SportVu data called Player Tracking Plus Minus (PT-PM) blended with RAPM and will follow up with another projection using ASPM Daniel Myers' boxscore based player metric.
PT-PM was developed using a combination of box score stats and SportVu stats regressed against RAPM data. Due to the newness of SportVu data, starting publicly only last year, data was limited. So I concentrated on building a stable model rather than over-fitting risking adjustments with unstable relationships, as a consequence the model leans towards mean reversion. The ESPN model, for example, has four teams in the West projected at over 60 wins using RPM. The PT-PM model, on the other hand, has seven western conference teams with over 50 wins.
The ASPM projections use two years of data weighted to the most recent year, which should give that model something of an advantage. Both models apply an aging factor and then run the numbers through the schedule with odds of winning calculated for each game, factoring in home court advantage.
Huge shout out to Kevin Ferrigan for providing me with his roster minute projections to start my analysis. I then made some of my own alterations, like to account for the momentous Joel Anthony-Will Bynum trade and the almost as important Kevin Durant injury. Minute projections are perhaps an underrated part of season projections, most of the methods used end up straddling the line between how much the coach would actually like to play his starters and the injury risks that end up striking somewhere every season.
Finally, to the numbers. Below both win projections are shown ranked via PT-PM in conference.
I am going to break these down more in another post, but a couple of quick potentially interesting things between these rankings:
- They have generally less of a consensus on the Eastern conference.
- PT-PM likes Miami considerably more than ASPM, specifically PT-PM like Mario Chalmers and dislikes Norris Cole less than ASPM. Some of that maybe the plus/minus DNA showing, I am not convinced that Miami won't have a bigger regression than that with the best player in the league gone.
- ASPM is still high on Detroit, that comes mainly from loving Andre Drummond, who scores a +2.97 in ASPM but has been rated more neutrally in plus/minus derivations.
- In the west playoff teams from last year look solid, save perhaps Portland.
- Kobe Bryant still scores decently in a two year ASPM since his disastrous minutes last year were so few, lifting Lakers perhaps unreasonably high.