Manchester United hasn't lost a game in the Europa, they drew 3 games and won 5 games, it's a good stat although only in the Europa since they have been incompetent in the Premier league, and over all performance isn't something to rely.
What could be the problem with this Manchester United team that they could get such a commendable stat in the Europa league and in 3rd position with just one point gap from Lazio and Athletic Bilbao, but are losing it so cheaply in performance in their domestic league. Is it that the English premier league is much tougher than the Europa league? Or they're giving much priority to the Europa league than they do with the mir domestic league games this season. If you ask me, I do see some strong teams in the Europa league stronger than some of the teams Manchester United loses to in the premier league so it's not really factually to just conclude that maybe the Europa competition isn't as strong as the premier league.