No, you clearly don't understand what I'm getting at.
Kawhi Leonard is the prototypical scoring small forward. He's a Paul George type guy. I'm sure he'll have numerous All-Star games, and in that regard he is better than Batum. I won't argue that.
Batum is a utility player. He's arguably the best utility player in the league. He scores, he passes, he rebounds, and he defends. The only name you could come up with is Tayshaun Prince, and Batum is better than Prince. He's a better passer, a better rebounder, and if you compare their numbers at 25 years old, he's a better shooter.
Utility guys like Batum are rare. Much rarer than scoring wings like George or Leonard. You don't appreciate that aspect of the game, and that's fine. That's your prerogative.
I will also point out that averages are a statistical fact of what actually happened. Rebound percentages and per 36 are projections of what could happen. There are other variables that could affect those numbers. The only fact that matters is that Batum averaged more rebounds than Leonard, so based on that fact, he is a better rebounder.