After being checked out by team trainers, Young walked off the field under his own power but with a noticeable limp. He smiled, though, and bumped fists with quarterback Michael Vick.
Before getting hurt, Young had gone 15-of-23 passing for 193 yards in the Eagles' 24-14 win. He threw one touchdown and no interceptions and had a 105.9 passer rating.
For a moment later in the game, it appeared another quarterback might have been injured when third-stringer Mike Kafka got crushed. There was no way the Eagles were putting Vick into the game, so wide receiver Jason Avant started getting loose, but Kafka remained in the game.
Young's injury came on a night that was mostly for players fighting to make one last case for a roster spot.
Coach Andy Reid rested all but one of his starters with an eye toward games that count, which for the Eagles begin Sept. 11 in St. Louis.
Stars such as Vick and running back DeSean Jackson spent the game in visors, safely out of harm's way.
Danny Watkins, the only Eagles starter who played, had an up-and-down game but was better than last week against Cleveland, when he was beaten early and often appeared confused.
There were no noticeable mistakes by the first-round pick, and he looked comfortable when he got a chance to block in the open field.
Kicker Alex Henery was one of the only key Eagles who played Thursday. He missed a 43-yard field goal on his first attempt, his longest of the preseason. Henery previously had gone 3 for 3 on field-goal attempts, a small sample, and not nearly enough to get a good feel for a rookie who will have a big job this season. (Reid passed up opportunities for two short field-goal attempts, opting to go for it on fourth down deep in Jets territory.)
Other Eagles who may be called on to fill in during the season had better evenings.
The offense moved the ball well behind Young, who solidified his hold on the backup job. He connected with Chad Hall for a pretty 16-yard touchdown pass to complete an eight-play, 91-yard drive led by the second-team quarterback.
After looking lost early in training camp, Young has improved all preseason.
Rookie running back Dion Lewis, a fifth-round pick, showed the elusiveness and versatility that almost certainly have earned him a spot on the roster.
Lewis opened the game by taking a kickoff out to the 37-yard line and finished the first half with 62 yards rushing on 15 attempts, with one touchdown, and 38 yards on three receptions.
Rookie linebacker Brian Rolle was active in a starting role, making plays, drawing a holding penalty, and notching 11/2 first-half sacks and a tackle for a loss. He has climbed in the coaches' eyes and was one of the first-choice linebackers in the nickel formation last week, when the Eagles gave their starters their most playing time.
As might be expected, other members of the Eagles' second and third teams had mixed nights.
Hall, after catching a touchdown pass, fumbled away the ball at his own 26-yard line, setting up a Jets score.
Trevor Laws, who had missed all of the previous preseason games, started at defensive tackle and tipped a pass. Cornerback Brandon Hughes gave up a touchdown pass on the ensuing drive.
Contact staff writer Jonathan Tamari at 215-854-5214, firstname.lastname@example.org, or @JonathanTamari on Twitter