A top class manager gets the most out of his team - makes them more than the sum of their parts, or, at least the sum of their parts.
Pellegrini didn't do it last year, and, on the whole, isn't doing it this year. Of course we have missed players, but considering the talent at our disposal, to not score in 4 consecutive away games (3 in the league) is really poor. Yesterday we didn't really look like scoring. Stoke, the lowest scorers in the league, carved us open a number of times, and should have scored 4 or 5; we, on the other hand, barely carved them open at all.
I'm not sure we have progressed over the last year or so. We started off like a house on fire, but that fantastic start has clouded where we really are. We are worse off than we were last season (and it was more or less accepted that we under performed last season.)
I hear a lot that we are prioritising the CL - but, Sevilla away aside, we haven't exactly blown teams away.
It will be interesting to see what happens when everyone is fit again. However, when 1 or 2 players under perform, that's football. When it's most of the team, then you have to look at the manager. Both seasons we won the league we lost 5, and 6 - we have already lost 4. Not being able to find the net against Villa was very disappointing, too.
I doubt we will sack a manager mid season, but he is rapidly losing the fans. And rightly or wrongly, the substitution of Dinho yesterday did him no favours, as you could hear by the reaction.
You can't sack a team of under performing players. You can sack an under performing manager.