Zekent's alt actually got up to 2419 on Poppy, while his main surpassed 2700 during the course of S2. If anything, his devotion to Poppy cost him Elo. Between dodging games where he couldn't play Poppy, playing Poppy in sub-optimal lanes because he couldn't go top, and the stream-ghosting and counterpicking that comes with the SpamHappy account's notoriety, I'm sure that Zekent had a ton of issues. He would occasionally play Poppy on his 2700 main, so she's viable at pretty much any level of play.