We're 15 points better off than we were at this stage last year and we haven't improved?

I'd say our record this year (W16 D4 L3) is significantly better that last year's W10 D7 L6 at this stage.
Last year we scraped into the top 4, I don't see how it's reasonable to expect us to win the league this year.
In order to assess whether we can win the league of course you have to look at how strong the other teams are.
City's squad is frightening, the fact they didn't win the league last year is a combination of poor management, Fergie being Fergie and RvP being brilliant and fit all season. They've looked far poorer this season with Moyes and with Rooney and RvP getting injuries.
We've also beaten Dortmund away (who I believe had won every home game prior to our visit), won away at Newcastle (who had only lost one home game and beaten both Utd and Chelsea at home at that stage) and beaten Liverpool at home (who would have leapfrogged us to go top had we not done so. I can cherry pick good results just as easily as you can cherry pick bad ones, and I can cherry pick bad results for our rivals (City lost away at Cardiff and Sunderland - the current bottom 2 - and, like us, drew away at Southampton)
I don't think we'll win the league because over a long season I think City and Chelsea both have too much for us.
You can blame Wenger if you like and of course he's not perfect, but we're competing with sides who don't have to cope with fatigue or injuries like we do. We've done well so far but when push comes to shove I think we'll be found wanting. The resources of City and Chelsea are a massive factor.
Do you think, given the last 2 seasons where we've just about limped into the top 4, the title is a reasonable expectation this year?