Anecdotally speaking, I’ve seen Draven more often being banned at least once if not twice in my lobbies whenever I queue ranked. But from checking stats website, he doesn’t seem too overpowered. What makes him such a powerhouse in the bot lane that requires a lot of bans?
Mostly because he completely warps the game around him. Either he gets ahead and gigacarries, or he falls behind and is completely useless and solo loses the game. Or, he’s a smurf who hard carries the game or he dies a couple times and AFKs because he doesn’t care about the account. No matter what the outcome of the game is, it is because of Draven. That kind of game is no fun to play.