I can tell from some comments that the commenter doesn't understand the evaluation method.
I'll explain it again and am happy to discuss.
I started with +/- only, as the best numeric measure of how well a 5 man lineup played together.
This lineup played 2:30 and we won 5-4. For each lineup change, there's a separate game segment. Add up the scores and assign to each player on the court at that time.
I believe in the value of that approach, as it picks up all the intangibles that don't show up in the box score, but make the difference between winning and losing. And obviously, if you are keeping track of the points we score and the points the opponent scores and the amount of time it takes to do so, you have a handle on defensive and offensive capabilities of every lineup (over time). Defense is a team effort.
That approach met with some legitimate concern that, say, Ryan Greer or Elijah Williams could stand out because they were +6 or whatever when he was playing and Boo Buie had hit a couple 3 pointers - in essence role players could get lucky when somebody else was doing all the actual work on the offensive end.
So I took the next step and started rating the contributions of the players - based on the only readily available information - the box score, and eventually the play-by-play. As far as I know, most of the major stats guys do the same thing. In some ways I feel like I'm ahead.
If we win by 15 points and we play the same 5 man lineup the entire game, each of those guys gets a +3 (3 X 5 = 15). Intangibles are assigned equally to the guys on the court. To assign credit or blame beyond that, each player's positive contributions must compared to those of his teammates. This is important and seems to confuse people.
I assume we average 1 point every time we have the ball. (its close enough) If you turn the ball over you just cost your team 1 point. If you steal the ball, you just deprived the opponent of 1 point. If you make a layup, the team gets 2 points, which is one more than we expect. So you contributed an extra 1 point. If you miss a shot, its very likely that the other team will get the ball. So that is -0.8, somewhat like a turnover. However, if you rebound your own miss, that has to offset the missed shot, so thats a +0.8. A 3-pointer is +2. An assist is +0.5. This approach puts a premium on efficient scoring.
On the defensive side, there are blocks, steals and rebounds. Not much to go on. A defensive rebound gets a 0.4. A steal is +1 and a blocked shot is +0.75 because your team usually gets the ball.
Free throws are based on making 1 of 2. If you make one, you get a +0.5. If you miss its -0.5. So if you make 1 of 2, you get zero points of credit because we expect 1 point every time we have the ball and thats what you provided. Defensive rebounds of missed free throws are +0.2 because they're easier. If you get fouled while scoring, the subsequent made free throw is +1 and a miss is not held against you. This puts the old school 3 point play on par with the 3 point shot.
So these contributions and mistakes are allocated to the guys on the court. If Barnhizer makes a 3 pointer, he gets a +2, but the 4 other guys get a -0.5. If Barnhizer misses a shot, everybody gets a +0.2 and Barnhizer gets a -0.8. If you are standing there watching your teammates play well, you will accumulate negative points as they accumulate positive points.
All of that gets added up for each player and results in a Player +/-.
The Player +/- is added to his Raw +/- (divided by 5 players) to get his Net +/-.
I'm pretty confident in this approach although minor tweaking could still improve it.
