Baines is still top-draw but to be honest there's no way Oviedo deserves to be dropped and the simple fact remains that we look better defensively with him there.
I'd mix it up a bit for the last few games of the season but then in pre-season I really would start to look at playing Baines in midfield and then that gives us another option heading into the next campaign.
It's unfortunate for Leighton but atm Oviedo definitely deserves his place. Against teams that sit back at home, I'd put Baines in though.