McCutchen over McLouth, seriously???
Look, I totally think McLouth is going to be overvalued next season. There's very, very little chance he'll wind up on any team of mine in a re-draft format. And if I had to weigh him against a veteran with a disappointing season but a longer track record (Alex Rios, Torii Hunter, Bobby Abreu, etc.), I'd go for the veteran.
That said, it's completely insane to take a guy who hasn't played a single major league game over him. Especially since his peripherals aren't discouraging at all. Excellent strikeout rate, good plate discipline, very good fly ball tendencies, well-rounded power and speed.
Maybe he's not going to be a 3rd or 4th round value, and maybe he'll get drafted there, or kept as if he is one...but don't think that McCutchen is going to storm into the league, replace him in CF, and be fantasy valuable for many, many years to come. The same goes for the other rookies, especially Maybin and Gonzalez. Those players will be All-Stars sometime in the future, maybe perennial ones early next decade, but unless you are in a dynasty league looking to rebuild for the long-haul, the choice isn't even close.
You mentioned Eric Byrnes, but the comparison isn't apt. First of all, Byrnes was killed this year by injuries. Second, I remember doubting Byrnes coming off his great 2006 season just as like you're doubting McLouth right now. And Byrnes made me pay in 2007.
In sum, overrated, sure. But the hyperbole on McCutchen won't cut it either.