Read my initial quote, I said "individual success". Coaches and players are not evaluated by the same measures entirely.
Stevens is a below. 500 coach, that is a fact (.401 winning per). By most measures that of not good. But obviously there are mitigating factors (i.e. the team he was charged with coaching). The playoffs is a feather in his cap, but that is about the only success he has achieved by coaching standards.
Cousins 1 All-Star appearance is at least equivalent in terms "success". Players are not primarily judged by wins and losses, as coaches are. His stats are a measure of individual success, so they are absolutely relevant to the discussion. DMC is widely considered the top center in the game and a top 10-15 player in the game. That is a star.
But you know what, I want BOTH.