It looks like the players have over trained at times this season. To run out of energy that early in the second half is amazing. As someone mentioned, it looks like they have run a marathon before the game. I think the lack of energy leads to the lack of quality. The same team with the same tactics on another day will play a heck of a lot better - we've seen it already.
You just don't know this season whether the team are going to turn up with enough energy and desire to win a game, because the quality is there and I don't think they are being hampered by tactics, despite what anyone thinks of the Fellaini substitution. Going forward, I think a fit team will beat Leicester this weekend and go and do the job away at Wolfsburg.