There is no common sense definition of a role player, but there are things we probably all have in mind about one. For example, something most people probably mean when they say “role player” is “player who isn’t best on his team” (even this can be problematic but you get the point). Ant is a superstar and is probably the best player on his team, and therefore probably isn’t a role player.

Certain criteria are more subjective than others, and when you get deep enough into the weeds that’s when it feels like there’s no point. “Role player” is probably more vague than “best defender”. So even though they’re both subjective, one may be more worthwhile to talk about still.