We don't know Vick wouldn't have thrown three touchdown passes and no interceptions, the way Foles did, against a defense that came in allowing 17.5 points a game. (We do know Vick hasn't thrown three touchdown passes in a game since Dec. 19, 2010, the miracle comeback game against the Giants that ended with the DeSean Jackson punt return for a touchdown.)
We don't know Vick wouldn't have managed a 133.3 passer rating against the Bucs, as Foles did in his first start of the season. (We do know the last time Vick posted a passer rating that high was the Nov. 15, 2010, a Monday night blowout of the Redskins.)
Is Chip Kelly going to make Foles the starting quarterback off this one game, plus the second half last week against the Giants?
"We'll evaluate everything," Kelly said. "Go back and watch film, see what we did good, see what we did bad, see where we are, see where Mike is."
Kelly said Foles "did a really good job of spreading the ball around to different receivers - really, really happy with how he played today."
Given the still-small Foles sample size, and the fact that Vick really hadn't been bad, making that change this week would be a huge upset. But if Foles were to start again this coming Sunday against the visiting Cowboys, play well, and win again? Much less of an upset, with Vick 33 years old and playing on a 1-year deal.
Last week, Kelly said Foles would have to "go 100-for-100 with 27 touchdowns" to supplant Vick as the starter. He didn't do that, but he did make a statement. Foles reopened the debate that Vick had closed by going 13-for-15 in a couple of preseason games.
It could be a temporary reopening, if Vick's left hamstring allows him to play this weekend. Neither Kelly nor Vick issued any proclamations about the Dallas game yesterday. Vick, listed as "questionable" going in, was active - Kelly said it was because emergency quarterback James Casey sat out with a groin injury - but Vick spent the entire afternoon wearing a baseball cap, a big pink breast-cancer awareness towel draped across his shoulders.
"You've just got to be cautious with an injury like this. You go out there and stress it out, you hurt yourself for the next 2 weeks, next 3 weeks. I just gotta make sure I'm 100 percent," Vick said. "I can't say right now" about Dallas.
"When you know you've got a quarterback behind you who can play, who will go out there and get the job done, the team believes in him, the guys believe in him, the coaching staff believes in him, you don't have to rush it," Vick said. "It's a good space to be in."
It's probably not a good space in which to linger indefinitely, though.
"Not at all," Vick said, when asked if he worried about losing the job. "Nick's a great football player. He does exactly what he needs to do when he goes out on the field. That's not something I'm going to worry about. I'm worrying about my health."
Asked if Kelly had assured him he would stay in the starting role, Vick said: "We haven't talked about that. It's no need to talk about it. We gotta go with the momentum, we gotta go with the flow. As players, we do what we're asked to do."
That was an interesting statement. One way to read it was that Vick might understand if Kelly reached a point where he wanted to stick with Foles.
"I don't worry about it," Foles said after completing 22 of 31 passes for 296 yards. He has now thrown 61 passes this season and hasn't been picked off. "I'm really proud of my team for winning right now. It was a hard-fought game, and I'm going to enjoy it with my teammates. No matter what happens, I'm going to be the same person. I know who I am, and Mike was tremendous tonight; Mike and Matt [Barkley], they were right there supporting me no matter what."
LeSean McCoy, who turbocharged the Eagles with a 44-yard ramble with a screen pass on the first snap, did not want to discuss the quarterbacking situation after rushing for 116 yards on 25 carries, as the 3-3 Eagles won back-to-back games for the first time under Kelly.
"Come on, we just won a game," McCoy said. "Mike is the starter, coach Kelly made that clear, but if he needs Nick to step in and make some plays, then he'll do that. He showed that tonight, he's proving that. Mike's the guy we go with, he's the starting quarterback, no matter what the town says or what the outsiders want. It's coach Kelly's call, and that's the call he's made."
Kelly made quite a few important calls yesterday, and they worked. He mapped out a dazzling, eight-play opening drive that ended with Foles, old leadfoot himself, chugging up the middle for 4 yards on a QB draw the Bucs clearly were not expecting.
"I thought it was really important to get out to a fast start, and I think the first play, we hit LeSean, he breaks one, and then all of a sudden, our guys start to get into a rhythm . . . I thought it was really important, especially playing a team like this team, we wanted to get out early, make them start playing from behind," Kelly said.
On the QB draw, Kelly wanted to make a point about running the same offense with Foles that he runs with Vick. Clearly, he shot down last week's meme about the Eagles not being able to run as effectively with Foles at the controls.
The game might have turned on a sequence that spanned the late third quarter and early fourth. The Bucs drove 90 yards, from their 1 to the Birds' 9, where they got a first down on a pass-interference call against little-used corner Roc Carmichael, subbing for a cramped-up Cary Williams. But the Eagles then forced Tampa to settle for a field goal, which kept the Eagles ahead, 21-20, and when they got the ball back, the Birds needed just three plays to make it 28-20, with Foles finding DeSean Jackson in the left corner of the end zone for the touchdown from 36 yards, a play after Riley Cooper took a hitch 44 yards.
"They were playing soft coverage. I got the ball to Riley, and he made a tremendous play, and really showed his speed and athletic ability," Foles said. "It was fun to see him run down like that. Then we had a little play-action pass called, and DeSean went right over the top of them and made a great play. It's fun when you have two plays like that in a row and you get some points on the board."
Red-clad fans started leaving Raymond James Stadium then, even though the winless Bucs were just eight points down with 9:32 left. Maybe they sensed the Eagles were going to force a three-and-out, punctuated by a Connor Barwin sack, then run the ball 11 times in a row, extending their field-goal drive by drawing the Bucs offside on a fourth-and-1 from Tampa's 17, when the Eagles had no intention of snapping the ball.
Foles now has both his career wins at Raymond James, having beaten the Bucs on the final play last Dec. 9.
"I felt like it was a home game," there were so many Eagles fans in the stands, Foles said.
On Twitter: @LesBowen