Let's not act like he's the worst manager in the world. Indeed, one of the more frustrating things about him is that he's too good to be sackable, but not good enough to really make anybody that happy to watch his Villa team.
Firstly, the good things. He actually has done fairly well in the transfer market considering he had to construct almost a whole squad with whatever money we could find lying around, down the backs of sofas, behind Randy's grandson's ear etc (and I'm not blaming Lerner for this necessarily - it's obvious we couldn't continue spending what we were). Especially in that £4-7m bracket he seems to have done rather well, with Benteke and Vlaar our most important players along with Gabby, and with both Okore and Kozak looking quite good before really unlucky injuries.
However, the last name - Kozak - is part of the big problem with our Paul. Not that Kozak's a bad player, far from it - I actually warmed to him more and more before the injury - but that Lambert fetishises the Big Man as the 'aerial option', and the fact that he sees that as a perfectly valid option will always, always, always hold him back, and us with him. His style is babyishly impatient, ordering the ball to be rushed to our Big Man as quickly as possible, and if there's no room in the midfield then we'll lob the ball over it, and lose possession.
This isn't to say that Lambert is bad tactically - far from it - it's just what he is good at isn't what we need at the moment. What he's good at is reactionary tactics, counterrattacking, finding ways to win games he shouldn't by planning for the opposition's best players, finding ways to hold teams at arm's length despite conceding 60%+ of the ball to them. He'd probably be good at the moment going in to a club like Swansea, who have a real stylistic identity but lack variation in their play - but he's never going to be the man to impose that identity, a vision of a style of play. That is what we need, and that's what real 'stability' would mean, but Lambert's football is not stable - it lurches, bumbles, hastily improvises, fannies along with no distinct plan and always with the very real possibility that it might all go tits up hanging around just out of sight.