I like Lee and Bannan, but I think we do need more strength in midfield. And up front.
We are clearly more effective with Forestieri coming in off the left, but in the bigger games I think Carlos played a 'proper' midfielder on the left, introducing Lopez/Hutchinson and shipping Bannan out wide to ensure we compete in midfield and pushing Fessi up front in a generally less effective attacking combination with Hooper than, say, Nuhiu and Hooper. He also stuck to 4-4-2 in general.
If we had a beast in midfield to play instead of one of Lee/Bannan than we could afford to keep Fessi on the left against the better teams. Hutchinson could be that beast but will inevitable be injured/suspended for a large part of the season.
If we had a proper lone front man that can score regularly (could be Joao if he progresses), then we have the option of playing 4-5-1 against the proper top teams with Fessi on the left with Bannan/Lee/new beast in the middle. This would mean dropping Hooper, but he really isn't effective on his own up top. Only Forestieri, Lees and Westwood are undroppable in my eyes.