PlusI think frustration (and to a point his personal circumstances) got the better of him.
Frustration at the apparent ceiling of the squad (compared to previous jobs) and also a ceiling on the clubs commitment to spend. Both should have been understood prior to taking the job.
I also think his illness probably made the situation seem far worse than the reality.
In the end he tried to distance himself from the failure, which let's be honest was a little cowardly. The players, coaches and club all played a part (just like the relative success of the prior season).
I always thought he felt we were a "modern club" (his words at some point) and it was an element he didn't like - new stadium and training ground, and he missed the traditional side to a club. I might be wrong but that's an impression he gave