People underestimate as to how tough the PL is, which is multiplied when managing a club the size of United and all it’s expectations.
Managers arguably better qualified than McKenna such as Gerrard and Lampard have quickly been found out in the PREM.
I don't think many are underestimating how tough the job is. Hardly any in fact. But I do think some people are seriously overestimating the extent to which previous experience prepares you for the job.
You seek safe hands, when there aren't any. Ten Hag is doing worse than Ole did in his first two seasons, on every conceivable metric. And yet the former was the inexperienced manager (Cardiff & Molde) and the latter was the experienced manager who ticked every box. Whoever comes, they'll have some serious pressure and they'll have to adapt and grow while on the job, if they are to succeed. Given the state of the club, their chances of long term success are minuscule, whoever that new manager is. Jose, LVG, Ten Hag have all failed. Is Tuchel a better, safer bet than those guys?
But now I have to ask, in what way were Lampard and Gerrard more qualified than McKenna?