You'd be surprised how untrue that statement is with regards momentum. Players are not as concerned with the league cup and when only 4 of those players that started tonight start on the weekend we really have a totally different side and that different side still has its momentum.
The reserves lost tonight
I sort of agree, especially regarding the players who didn't play, but our next game is at home and the fans who did bother to go tonight (not me) will lose any feel good factor we had from the first two games IMO. The atmosphere is already as tense as you'd expect for a team with our home record, this will make it worse.
I also think you're possibly lowballing with 4 starters from this team at the weekend.
If we beat Hull then this will be disregarded but if we don't it will feel like the start of the bad run to all of us.