I'm sure there's a doctoral student in sports management out there somewhere who's writing his dissertation on Ole's failures as United manager, but I'll boil down my criticisms to a few points. But before I go there some of the criticism has to be laid on the laid on the players themselves. I'm thinking of Maguire and Wan-Bissaka. These two were highly regarded players at their previous clubs and it's at least my thesis that their horrific performances are almost entirely their fault, not Ole's. Yes, Ole rushed Maguire back from injury but Maguire has to take responsibility for his own actions, which to date I no evidence that he has. With that, the following:
He leaned too heavily into developing an English core...a key (mythical) component of the "United DNA"
He failed to strengthen our midfield
He was tactically too stubborn
He should have pressed to acquire for Sancho last season
Points 1-3 are probably not controversial, but I suspect Point 4 is. Let me explain myself.
Sancho was there for the taking in the summer of 2020 for what I believe was 107m, which went down 87min the summer of 2021 when we bought him. Saving 20m is no small matter from the Glazers' point of view, but last season would have been the perfect time to bed Sancho into the PL so that he'd be in top gear at the beginning of this season. But more than that, having Sancho on the squad last season very likely would have made the difference between crashing out and not crashing out the CL at the group stage last season. Had we gone in for Sancho last season and, in order to cash that was otherwise wasted, we not brought in Van De Beek, we would have had the winger we needed and not wasted cash on who appears to be a player Ole never rated anyway. It also seems likely that had we gone in on Sancho the previous season we would likely not have wasted the 40-50m we appear to have wasted on Diallo and Pellistri, two other RW players who are nowhere close to being first team regulars. Sure, we'll get some of that back when we sell them, but we'll undoubtedly sell them at a steep loss.
Bringing in Sancho last season would not have abated the club's epic meltdown this season, but we may well have put in a much better overall shift last season -- either going deeper into the CL or perhaps, if still crashing out of the CL, actually winning the EL final. And maybe, just maybe, had we gone in for Sancho in the summer of 2020 we would have gone in for a proper CDM last summer, although it seems more likely than not that Ole really believed we didn't need a CDM given the obvious masterful performances of McTominay and Fred.
The root of the problem is the rot at the top, but that rot extends to the kind of ridiculous player management decisions -- overpaying for an average CB but suddenly being pennywise/pound foolish on a world class RW -- that Ole was willing to accept as the price we all had to pay for his glee that he was given a job he and everyone else knew he unqualified to cope with.