I think that will be a huge factor, particularly for Berry and Ruckert, in how much they play. If there's a significant drop-off in blocking when Berry or Ruckert is in the game, then they're not going to play much. I don't see the Buckeyes substituting tight ends in and out of the lineup play after play based on whether they're going to throw or run, so the most complete player(s) – at this point, presumably Farrell – will play the most. That said, I wouldn't be surprised if they use all three of those tight ends in slightly different roles, particularly Ruckert, who I could see being split out like a wide receiver more than playing a traditional tight end role for this season. Either way, though, he's going to be able to block effectively in the run game regardless of where he lines up, because that's a big emphasis for Ohio State's wide receivers, as well.
Worth keeping in mind that at this time last year, Ohio State had a wide open competition at right guard (and Bowen, who ultimately won the job, went into fall camp working primarily at tackle), so it's not necessarily unusual for the Buckeyes to be experimenting with different offensive line combinations in August. That's not to say it isn't a reason for concern, but they're likely going to be experimenting with various lineups at all positions over the next couple weeks before they really begin locking in their depth chart for the start of the season.