To be fair to them, he's better than the replacements they could've gotten where they are now. By the looks of things, Arsenal may well be too big of flat track bullies at home to even let them get a sniff at a top four and then it's do-or-die on the Europa this season. At least that's something they in theory could get done, save for some flashy team getting knocked out of the CL groups. The way they've played this season and the state of their midfield still probably means they'll find a way to miss out on both their chances of getting back to the big table and as such, Dave's decision will not do him any good.
Leverkusen and one of Dortmund/Inter + one of Chelsea/Valencia/Ajax are likely to get dropped into the EL though and I really doubt United would be clear favourites against either of them right now.