It's a bit of a strange one as Gerrard did eventually come good at Rangers after a couple of very mediocre seasons and 38 player changes(apparently). That said, it's a totally different situation, as Rangers was a big team in the division, so had high levels of possession and also could afford to be patient.
With other teams around us improving, it's getting tougher to break the top 8 and I don't think we can afford that amount of time to see if he comes good. Personally I haven't seen enough potential from him to suggest he will get to where we need him to. I'd like to be wrong but I think the odds aren't in his favour.
We pretty much know that NSWE and Purslow expect 7th this season.
So their thinking will be can Gerrard get 7th or not? If not, cut losses sooner rather than later. It's a gamble to keep him and a gamble to sack him.
29 games (2/3 of a season) into Gerrard's reign and they will be asking whether he has improved Villa on the pitch, both in results and tactically and by coaching of individual players.
After 29 games the answer if currently a resounding no.
Lets say he wins 4 out of the next 10 games. Even that only makes his record for Villa average over a whole season (39 games by then).
He now needs a massive swing in his favour before the world cup to be able to salvage his managerial career at Villa.