"Well it's very hard to tell you know," he told BBC Sport. "The team has stayed more or less together obviously and the manager stayed there and he got the chance.
"When you win the league in your first season it's the best possible start because obviously people get to trust you. I think you make yourself a name and the players know you, the continuity can be there.
"So sometimes it is very surprising when the odd season goes completely wrong. It might be just the fact that something goes slightly different and you try to think too much about it and then once you get in a few bad results on the spin it can change the confidence of the team."
Chelsea battled past Leicester City on Sunday afternoon to set up an FA Cup semi-final showdown with Southampton next month.