I also have some ideas of how to improve the WS/48 and MPG statistics to be more meaningful but will share them when I do some work on that
Too box based for my liking. Some sort of advanced plus minus (for a 3-5 year stretch) should be included in the stat adjusting for role and noise that comes with plus minus stats.
3-5 years of data would be great, especially for getting a better handle on guys who are playing low-rotation minutes but are getting great real plus/minus scores. What gives with them? Is their coach missing something, or is the stat missing something that the coach isn’t? Beyond that, is the stat also measuring how effective the coaching is, since it’s measuring how effective a player is in the role he’s playing?
I think the risk in that much data is that you’re measuring too much. Players get hurt, They miss time or play hurt, someone else gets hurt so their usage increases and they get more or less efficient, their roles change and they have to guard bigger opponents, they get traded and their minutes change, etc.
Having said all that it would be worth a lot to be able to use an RPM app in which you could specify the time-frame of the data.
I think that ESPN’s RPM is an indispensable stat, despite their mediocre presentation (for a start, you cannot search or sort by player or team).
But it has problems. Box score priors are incorporated, but how? How important are the box data? The more important they are, the more the stat is weighted toward players who put a lot in the box score; but if Ojeleye gets a deflection that leads to a 24-second violation, or a bad shot, or a steal that another Celtic gets credit for, the stat is undervaluing him. Perhaps in my RPM app you could dial in the amount of box score data...