Not sure you can compare United and Chelsea as clubs to be honest, how many times do we hear a player just can't hack playing for Manchester United(which isn't a criticism), or can't hack playing for England, then how many times do we hear a player just couldn't hack it playing for Chelsea, it just doesn't happen, so there's less hit and miss with new recruits for starters making it easier to bring the right players in to improve the team instantly, and that's before you factor in the 592 players they've got out on loan at a good level all ready to take their chance if they can't get the player(s)they want - Chelsea got lucky with Tuchel, it may well have gone the other way, and just because it worked at Chelsea doesn't mean it would work at United.
I don't think the injuries played that big a part for Liverpool last season, they still had the midfield which makes their team tick, and still had the feared three up top, they were just found out, and it's to their credit that they've ironed out any issues and are up and running(literally)again this season - thought it was cute how many in the media defended them over their injuries, yet conveniently turned a blind eye when United went nearly three years and having 8/9 out was the norm and at times it was in double figures, but then they always have been the medias darling.
Fair enough on the 2nd half of last season, but we don't know if we'd not been still in the Europa League it would have been the same, it was a brutal season fixture wise and the team did well with a smallish squad to keep going in both comps for me.
Tiss a mystery what's happened this season after a good start, and I don't believe a new Manager is suddenly gonna turn it around, not until he or she move on those that have far too much sway in the dressing-room, and I think most of us know who they are.