The problem with Pochettino was that he followed the Bielsa model, but only up to a point.
He came in, started bringing in talented young players, reduced the average age of the squad massively, and got them playing a highly-charged pressing game. This worked brilliantly for about three seasons, then the squad hit a wall last season. We all saw it, but many turned a blind eye as we stumbled into the CL final and top 4 more by accident than design.
Bielsa would regularly refresh his team to keep the squad full of young and energetic players. Pochettino did try to do this (most of our signings and targets were young, up and coming players), but I think he misjudged how long he could continue with the press with an ageing squad, as well as being too attached to players not suited to his system. This season he tried to find a new system to accommodate them, but couldn’t.
As for the players themselves, I think a lot of them feel guilty for getting Pochettino sacked, and are also probably still demoralised by blowing their big chance in the CL final. After the high of making the final I wouldn’t underestimate the low of losing in such an insipid manner.