I disagree. Donovan is one of the top five quarterbacks in the NFL. No, make that top three. Only Peyton Manning and Tom Brady are better. Like Brady, McNabb gets it done with no credible wide receivers. Heck, McNabb made Donte Stallworth look like a superstar.
McNabb has really progressed into a top notch QB. He's playing his best football right now.
McNabb is good for the same reasons that Vick is good - they both can avoid sacks and make the defenses worry about them gaining first downs with their legs on 3rd and 7 type situations.
McNabb is a much better passer at this point but he still isn't all that accurate. What makes him a top five QB (I will agree with you there) is that he is able to keep drives alive by avoiding sacks and running for crucial first downs.