His mind quickly eliminated the deep ball, the post or the crossing route. He absolutely knew DeSean Jackson was running an out route. And as Vick flicked the pass from his left arm, Jenkins absolutely knew he would break it up.
Jenkins extended his left arm, using proper technique, but Vick's throw was more to the outside than he anticipated.
Jackson caught the ball at the Philadelphia 19 and was not touched again until Orlando Scandrick dove at his heels at the Dallas 10.
The 91-yard touchdown pass was the second-longest given up by the Dallas Cowboys in their history and took all of 19 seconds to turn a tie score into a 27-20 Philadelphia Eagles' lead with 11:24 to play.
If Jenkins had to do it again, he would do it the same way.
"Always," Jenkins said. "That's what makes a corner. You've got to be aggressive. You've got to gamble or else you're going to be meat out there. That's why I was trying to go for the ball, trying to make a big play."
Big plays -- not just the 91-yard TD -- led to the Cowboys' 30-27 loss to Philadelphia on Sunday at Cowboys Stadium.
In addition to the 91-yard grab, Jackson had receptions of 60, 37 and 22 yards. Running back LeSean McCoy had a 56-yard run, the longest given up by the Cowboys this season. McCoy had three other carries of 12, 19 and 13 yards.
In eight plays, the Eagles picked up 310 of their 429 yards.
"They're certainly a big-play team," Cowboys defensive coordinator Paul Pasqualoni said. "They had some big plays. They've had big plays in every game. Regardless of who you're playing, you're always trying to keep the big plays to a minimum. Big plays are a big factor in this league in determining winning and losing. The turnover battle is No. 1, but big plays are up there pretty high."
Vick matched his season total with two interceptions (Gerald Sensabaugh, Bradie James). He was sacked twice (Jay Ratliff, Orlando Scandrick), but it seemed as if he was hit more than he had been in any game. DeMarcus Ware got him with a blindside hit. Anthony Spencer got a 15-yard roughing-the-passer penalty that will certainly draw a fine but also sent a message.
For 47 defensive snaps, the Cowboys held up. Eight snaps did them in.
"Very frustrating," Scandrick said. "You've got to play a complete game. We talk about being at our best for 60 minutes. We didn't do that."
Big plays played a large part in former coach Wade Phillips' midseason dismissal. In the first eight games, the Cowboys allowed 27 pass plays of 20 or more yards and 29 running plays of 10 or more yards. Entering Sunday's game, in the four games with Pasqualoni calling the defense, the Cowboys allowed 15 pass plays of 20 or more yards and just three runs of 10 yards or more.
Yet despite the big-play trouble, the defense had a chance to give the offense a chance to tie or win the game.
After Jason Witten's touchdown catch cut the gap to three points, Philadelphia took over from its 10 with 4:22 to play.
Dallas would not touch the ball again. McCoy had carries of 12, 19 and 13 yards. The Cowboys used their timeouts, but on third-and-1 from the Dallas 31, McCoy picked up 6 yards.
"It's our job to stop those guys," linebacker Bradie James said. "I have no idea. I know the play but I don't know where it was hitting. But being a realist, you know they're getting ready to run the ball, so you've got to find a way to stay in your gap and stop the guy."
The Cowboys did that some Sunday. Just not enough.
Sort of like this season.