When Kelly took a deep breath and went with rookie Matt Barkley, Vick went to the bench and draped a towel over his head. He has been in the NFL long enough to know that it isn't a good sign when three weeks of rehabilitation come undone in just nine plays.
"I tested it many times, but there's nothing like game simulation when guys are coming at you and they are going to hit you," Vick said. "I just reacted the same way I would have if I was 100 percent healthy."
He scrambled away from pressure and ran out of bounds on the third play of the Eagles' third drive of the game. The hamstring popped like a violin string turned too tightly, and after that it was just a matter of how long Kelly would choose to stay with him.
"It was hurting," Vick said. "I can't question why it happened. I've never had a hamstring injury this bad, so I really don't know what to tell you."
He has never had a 33-year-old hamstring before, either, and that probably explains the problem. Most of the other injuries Vick has suffered during his time with the Eagles had to do with the nature of football, and would have happened to a 20-year-old as easily as a 30-year-old. Bruised ribs, a hand injury, a quadriceps bruise, a concussion. Quarterbacks get hit and quarterbacks get hurt.
Vick has yet to be hit either time his hamstring went on him, however, and he also was merely trying to avoid contact when he suffered groin strains in the first two games of the season. He isn't being broken by defenses, which can happen to anyone. He is breaking down, which is much more likely for a veteran who has played in 127 regular-season games.
This leaves Kelly with a difficult decision, particularly since he isn't awash in great quarterback options at the moment. Vick was the starter against the Giants because Nick Foles is out with a concussion, because Barkley is a rookie whom the organization might or might not like all that much, and because Vick had gotten himself to somewhere around 80 percent of his normal capability.
Kelly went with Vick, giving him almost all the practice work with the first-team offense, and hoped for the best. What did he get? Eight healthy plays and a reinjured quarterback on the ninth. That's far from the best.
"When you're unsettled at this position in this league, it's real difficult," Kelly said. "Right now, we're unstable at the quarterback spot and we are not playing well at the quarterback spot, and we lost our last two games because of it."
Foles didn't have an excuse for playing three awful quarters against Dallas before suffering his concussion, so not everything can be blamed on an unsettled situation. Since that happened, however, with Barkley trying to salvage both games - once in relief of Foles and once in relief of Vick - it has been something of a fire drill.
The coach sounded like a man who isn't going to put himself in that situation again, and that means nothing good for Vick. If Vick can't be trusted to stay on the field, Kelly will be less willing to give him all the practice reps and put him out there.
"When it was originally diagnosed, it was supposed to be 10 to 14 days. It was actually 21 days until he played. So he felt good about it. Our training staff and doctors felt good about it. We as a coaching staff didn't see any effects . . . from a practice standpoint. [We] felt he was going to be the number-one guy," Kelly said.
And he was, until the ninth play.
If Michael Vick can do everything right during the week and still be the wrong guy on Sunday, then he isn't the right guy during the week, either.
Kelly has made that mistake once now with his 33-year-old incumbent. We'll find out soon whether the new coach considers it a learning experience.