The Blues smashed Arsenal 6-0 - following on from home wins this season over Manchester City, Liverpool and Manchester United - but a week later lost at Crystal Palace before falling to a 3-1 Champions League quarter-final first-leg loss at Paris St Germain.
With six games remaining in the Premier League, Mourinho is preparing for the visit of Stoke, live on Sky Sports on Saturday (kick-off 17.30), knowing victory is crucial as they look to catch up on leaders Liverpool.
"I don't know if we are going to have a fantastic performance or not," said Mourinho, whose side were beaten in the reverse fixture in December.
"Part of the stability of the top teams, of the teams full of people with experience, is exactly that stability.
"We are the team that during the season we have ups and downs. We have players that were not capable to keep a platform of stability in their performances. We had a few players with these ups and downs."
Mourinho was scathing in his criticism following the Selhurst Park loss and Fernando Torres was omitted from a striker-less starting XI at PSG on Wednesday, even though Samuel Eto'o (hamstring) is injured.
The Portuguese boss insists Torres has a future at Chelsea, despite wanting more from the much-maligned World Cup-winning Spain striker.
He added: "Since the beginning of the season we tried and we thought about the possibilities of different qualities. Different strikers, different qualities.
"Fernando is a player with a certain profile and will always be the player with that profile. It's not at the age of 30 years old that he's going to add new qualities to the qualities he has.
"He gives what he can. We respect that. I respect that. That's why he keeps playing, we keep trusting him and we believe that he still has things to give us."