Right now, the larger hockey analytics community measures possession by shot attempt or scoring chance differential when a player is on the ice. These are commonly called Corsi or SAT (all shooting attempts) and expressed as a percentage, i.e. CF% or SAT%. Scoring Chances are expressed in the same way (SCF%). The thinking goes that if a player is on the ice for more attempts for his team than against, in the long run that team will win more games and score more goals than not. All of this makes sense and I agree with it. However, is this the best way to measure possession?