Don't worry, he stayed in the game after this tumble, and the 22-year-old likely learned a valuable lesson about situational awareness to boot.
If he had slipped and managed to catch the ball anyway, well, it still wouldn't excuse having the bullpens in foul territory, but it at least would have been a highlight-worthy moment for a different reason. This isn't meant to bash Tropicana any more than it has been, by the way: it's not the only stadium out there that still has its bullpens in what seems like a super obvious dangerous place. Remember earlier this month, when Darwin Barney slammed into the bullpen bench at Wrigley?
It costs money to fix these sorts of things, though, so expect change to be slow. Especially since it's not just older parks like Wrigley or Tropicana that have these things in them: newer stadiums like Petco Park have been guilty of foul territory bullpens, too, until recent modifications put the visiting bullpen out of play, just like that of the home team's.