There is one possibility that solves 2 riddles. I'm not saying this is likely what he's doing but we'll see. But what if Deila doesn't think Medina is part of the best 11? Maybe he plays him against San Carlos because they're weak, and Taty and/or Isi aren't fully match fit. Then he keeps playing Medina in MLS because he's a rotation player, and he's saving those guys for CCL. Chanot forced additional rotation bringing in Parks and Ronnie figures that's enough and everyone else can handle 2 games on 3 days full rest (Toronto and Tigres), and the more complete rotation will come against Dallas.