I am in total agreement with you about having a real crack at the Europa League.....but the F.A. Cup doesn't have the same immediate impact as the EL.
There is a week between the F.A. cup tie and the next league game, as opposed to the two clear days between the EL fixture and the next match.
There are no journeys to the ass hole of Europe in the F.A. Cup.......though there are many to the ass hole of England
Ergo no long flights back home for the team in the early hours of Friday morning.
So I don't think Bobby has the same freedom to go with his best XI in the EL as he does in the domestic competition......he has to keep one eye on what is coming down the pike sixty or so hours later.