Much of my conjecture over my past few post has been flawed, but at least it's an attempt in growing.
Here, I will lay out the foundations of my current, modified EMA (or Efficiency Margin Added).
This shows each player's increase in the points per possession his team scores on the floor.
First, I gotta define a few things:
ON = PlusMinus (+/-) while a player is on the court
OFF = PlusMinus (+/-) while a player is off the court
Net = The points a player scores, minus the points his man scores
Min%=percent of game a player plays in, or percent of minutes played
here are two basic estimations for how much one player helps his teammates (which I call TMA, or Teammate Margin Added). This is a factor based on their substitution, i.e. how many points a team stands to benefit by a player being in (how good they are on the court minus how good they are off the court).
TMA1=2 x (Teammates' Net While On Court - Teammates' Average Net)
^for this one, we estimate that they add just as much as they do on the court as their team loses when they are off the court
TMA2=Teammates' Net While On Court - (4/5 x OFF)
^i.e. their four teammates make up roughly 4/5 of the point margin while a player is off the court
So we get our estimated Teammate Margin Added (eTMA) by averaging these two estimates.
now, we need to find out what a players' Net is, adjusted for how good his teammates are (adjusted Net, or aNet)
aNet=Net-(1/4) x (All Teammates' Total eTMA)x Min%
The 1/4 multiplier is because each player helps a sum total of four teammates while on the court.
Then, a players' overall Point Margin Added (PMA) simply adds our two estimates:
and per possession, we calculate EMA as
EMA=PMA/(Team Possessions Played x Min%)
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