Sports fans can be notoriously fickle. While they berate cheaters on the cover of tabloids for taking performance enhancing drugs, when that cheater makes a home run in extra innings to win the game, those same fans stand up and cheer. There is probably an entire section of academia devoted to studying sports psychology but it seems like in any other arena, people have a morbid fascination in constructing and deconstructing their heroes.
The Eagles are taking an enormous risk, but if they had not, it seems inevitable that some other team would have. Vick was arguably one of the best quarterbacks in the league when he was ousted. Whether prison freezes time, and Vick is capable of rising to perform at the level required to stay exceptional and stay alive in the NFL won't be known at least until the last two pre-season games of the year, and perhaps not until game six during the regular season if he is reinstated completely into the NFL and allowed to suit up.
As far as comebacks go, I just enjoyed watching Lance Armstrong's in the Tour De France. It isn't a contact sport unless of course you begin to factor the damage that contact with the ground can do while descending the Alps or the Pyrenees at 50-60mph on a 14 pound two-wheeled sled. Given that Lance didn't "win" the race for several reasons, the most important being that he was not the best cyclist in the race, the fact that he was able to place on the podium after such a respite is an exceptional human achievement. Perhaps Lance is truly riding for a cause higher than himself, but Vick doesn't have a legion of Cancer survivors cheering him on.
Regardless of how many photo opportunities Vick's work with the local Humane Society generates, he has to become comfortable with the fact that he will always have detractors that would like to be as brutal to him as he was to those dogs. Perhaps more painful will be the number of times he will have to explain to his three young children why people stare at their dad the way they do.
In a sport that has ceded some of its gladiatorial tendencies to Ultimate Fighting and Mixed Martial Arts, there is now a clear villain for mobs in the stands to root against. Week after week, in one arena after another, there will inevitably be an added tension when Vick takes the field. Will the ultimate punishment be meted out by a dog loving linebacker who makes a late hit, after considering that a fine maybe a small price to pay in order to make Michael Vick feel like one of the dogs he abused?