You're right about numbers relating to an average amount of time a player holds the ball per each team possession. But wouldn't pace be irrelevant when you are talking about the percentage of time a player has possession when on court?
Ah I see what you're saying -- faster offense shorter time of possession for each Rocket. So the numbers are useful for comparing as between Rockets (or Rockets and other fast paced teams) but not so much between Rockets and other regular teams' players ... Good point