The 5-3 hammering at Tottenham last season forever altered Mourinho & thus Chelsea. Chelsea were only the best side last season up until New years Day. Pochettino tactically destroyed Mourinho by targeting Fabregas & Matic by telling Eriksen to drift out to the flanks taking Matic, who Mourinho told to man-mark Eriksen, with him thus leaving Fabregas horribly exposed vs the likes of Kane, Chadli & Co all running at the slow CB back pairing of Terry & Cahill. Pochettino knew Mourinho would try to destroy Eriksen's link up play with Kane as that was the main attacking threat from Spurs up until that point. Mourinho is above all else a reactive manager. Pochettino foreseeing this, countered Mourinho's destructive game-plan. By exploiting Mourinho telling Matic to man-mark Spurs' playmaker, the consequences were it destroyed Mourinho's nerve in having an attacking gameplan & he doubled down on negative football so as not to get hammered again telling the rest of his midfield to tuck in to protect Fabregas being a liability in defence. So shook was he by that result, that for the rest of the season, they just stumbled over the line. There were half a dozen games in the 2nd half of last season where Chelsea needed goalkeeping errors to gift them the 3 points. In truth, Chelsea haven't attacked well since January 2015. But this has long term consequences that we are only beginning to see this season. Don't underestimate what this negativity does to the Chelsea players. When your manager doesn't believe you are capable of outplaying & outscoring the opposition, then confidence drops like a stone. How can you believe you can take the opposition on when your manager is drumming into your head that the main playmaker in the side is so bad defensively, that the entire team attacking approach must be sacrificed to shore up the team? The players don't have the belief anymore that they can attack well because the manager tells them though his tactics that he fears the opposition scoring more than trusting the attacking threat of his own players. He has destroyed their confidence because he has no trust in them in an open game.
Mourinho is, of course, trying to do what he did in the 2nd half of last season by grinding it out but the players have had it. Close the game down? Why? Why should I bust a gut for a manager who doesn't believe we are good enough to attack? You can do that for 3 months when the prize is in sight but over the long term? He has lost the players subconsciously because they don't want to play like Pulis' West Brom, no disrepsect to WBA fans, shutting down games all the time. He tried it today vs Liverpool but the mental energy has gone. He has sucked all the joy & belief out of them. Eventually, you get sick of it. For those Chelsea players, it's not a pleasure to play football anymore, it's a slog to shut down games when taking the lead because the manager doesn't believe in your attacking threat & the longer the slog goes on, the less you try. Morale has collapsed.