I've always said pre-season friendlies mean nothing but a win is good for moral regardless, when we beat Roma a lot of blues were hyping up players then when we got battered by Madrid it turned into which players aren't good enough.
It's about fitness building and getting prepared for a long season, this win against Barca will have a drastic moral boost on the United players going into the season and much like Hart said after the Madrid game big losses can't be allowed to get to the players mentality.
United are using this preseason to bed in the new signings they've made as we're using this to employ a new system and style of play.
I can see us possibly winning the league this season to be fair and I'd be more confident if we make 2 really good signings before the window shuts, I can also see united finishing 3rd or 2nd depending where we fall.
Chelsea COULD suffer with City syndrome from last season making very minimal changes to the squad as they'll go into the season with the mentality of that they have a league winning side so therefore don't need to make drastic changes, that's why it's always harder retaining the league.