On a tangentially related note: I came across "Regularized Adjusted Plus/Minus" stats for NBA basketball players today. They are essentially exactly the stats we're using in FIRST! See for example,
this link.
In our terminology, they view each basketball possession as an "alliance" of 5 players versus a defensive "alliance" of the 5 players on the other team. They count each possession as a "match" and then compute the stats just like we do. Every time a new player is subbed in, the alliance changes. "Raw plus/minus" is just like the averages discussed in the paper. "Adjusted plus/minus" is like sOPR and sDPR (compare the first equation in the link above with the equations on page 6 of the paper). "Regularlized adjusted plus/minus" is just like the MMSE version.
This link shows ORPM, DRPM and RPM for NBA players which are essentially just like sOPR, sDPR, and sCPR.