I agree, our ball retention was poor yesterday, but with time and finding the right balance of the team, it can only get better.
Back five seems fine. We can finally say we have a stamped down back five. Two very good ball playing centre backs, flanked by two well rounded full backs.
Then you move onto the midfield. A lot of people, including myself said that we could really do with a deep-lying playmaker. Someone, as you said, thst commands the ball off the back four and starts attacks. However, Ole obviously didn't feel the need for one, and it seems he has gone with Paul Pogba to fill that role. Now, as you mentioned, Pogba was poor in possession against Chelsea, but I can't imagine he'll always be that bad. Pogba made 63 passes, with a pass accuracy of 76.2%. He was also dispossessed 4 times. Not great reading for a deep-lying playmaker! That said, he also made 4 key passes and bagged himself 2 assists. Going forward, I expect Pogba to be much better in possession.
Moving futher up the pitch we had three players behind the forward which consisted of Rashford, Lingard and Pereira. The midfield rotation between them wasn't great, and the lack of involvement on the ball would suggest they were scared to receive the ball.
Passing stats were:
Rashford: 22 passes - 59.1%
Lingard: 26 passes - 88.5 %
Pereira: 15 passes - 73.3%
Not only is that a dreadful reading in terms of thier passing accuracy (except Lingard), as I said above, the number of passes are quite low, especially Pereira and Lingard, who were roaming playmakers, as opposed to wide forwards like Rashford.
Again, going forward that will definitely need to improve and I imagine it will.
We haven't got a lot of top class options in the final third, especially players who find a pass, but I would prefer Mata to come in for Pereira, as he is very good in possession. I'd keep Lingard in there as he's a link player, and Rashford can continue to play the wide forward role.
I do think, with all that's gone on last season, and the end of last season with Ole, the players were nervous. Obviously, that doesn't excuse the silly flicks and tricks we saw, as you pointed out, but having won convincingly against a side you'd expect to be in and around top 6 this season, I personally feel it will give us the confidence to go out and play better football next game.