My problem with him is a step back from that - I don't necessarily think that Bent the striker's bad, I think Bent the footballer is.
To use a different analogy to your car: I work in events and I might be fantastic on the day - efficient, friendly and professional; great, but if I can't book venues or create my presentations or do any of the other 'backstage' stuff that goes with it then I'm not good at my job. There are two ways to deal with this: if I'm really outstanding at the "on the day" stuff, create me a role that's just doing that. If I'm not, I'm not up to my job and I should go.
Bent might be doing ok goal-wise, but he's not outstanding, and he's not doing the 'backstage' stuff either, which is why I don't think he's up to it.
I don't think he's terrible, but he's not a great, and that's why I give him grief when he messes up. I do concede he's had it a bit hard this season in particular, and I do bear that in mind (I don't dislike him as much as I could/have), but he's not done anything to shut us up either, which is why I give him stick.
To be honest though, he's not moved me enough recently either way to care all that much.