An MRI on Monday morning confirmed what the Jets suspected after their 54-13 loss to the New England Patriots -- a Grade 2 sprain to the posterior cruciate ligament.
The Jets have to make a decision about whether to place Wilson on injured reserve, which would sideline him for a minimum of three games.
Saleh said they will know by the end of the week whether it's a two-week injury or a four-week injury, noting there's a "possibility" that Wilson might be able to play Nov. 14 against the Buffalo Bills.
"Thankfully, it's not a serious injury," Saleh said.
Mike White, who made his NFL debut Sunday, is expected to start this Sunday against the Cincinnati Bengals at MetLife Stadium. Adding quarterback insurance, the Jets re-acquired Joe Flacco in a trade Monday with the Philadelphia Eagles. Flacco was the Jets' backup last season, going 0-4 when replacing the injured Sam Darnold.
Wilson's injury is a blow for the reeling Jets (1-5), who made the former BYU star the focal point of their rebuilding plan. The No. 2 pick started the first six games. Even though he's struggling -- ranked 31st out of 32 qualified quarterbacks in Total QBR -- he's gaining valuable experience.
The upside is that Wilson, without any setbacks in his rehab, should be back to play the final seven or eight games.
Saleh said the "silver lining" to the injury is that Wilson will be able to watch how another quarterback runs this particular offense -- a learning experience.
"I don't think it's a setback," Saleh said. "I think it's always good to be able to step away and watch the offense through the lens of another quarterback."
Wilson said his knee "twisted" and he "felt a pop" on a second-quarter hit by linebacker Matt Judon, who blasted the young quarterback as he heaved a long pass. Wilson limped to the locker room and watched the remainder of his game on his smartphone, already rehabbing his knee.
Five years ago, almost to the day (Oct. 23, 2016), Judon ended the season of Jets' quarterback Geno Smith, who tore an ACL on a tackle by Judon. At the time, Judon was playing for the Baltimore Ravens.
The Jets left themselves vulnerable at quarterback by opting not to sign an experienced backup. They entered the season as only the fifth team in the past 10 seasons to have no quarterbacks with NFL experience on their Week 1 roster, according to Elias Sports Bureau data.
White, a former Dallas Cowboys draft pick, threw a 3-yard touchdown on his first pass, but he finished with two interceptions. He completed 20 of 32 passes for 202 yards.
"Yeah, I'm confident in myself," White said after the game. "I'm mostly confident in the guys we have in that locker room, the leaders we have. The coaching staff, too."
As the backup, White hadn't taken any first-team reps in practice. This week will be a crash course. Running back Ty Johnson expressed confidence in White, saying, "He's a stud, man. Come on now. That's Mike White."
The Jets are getting crushed by injuries, especially at linebacker.
Sherwood, a fifth-round pick from Auburn, was making the transition from college safety to linebacker. He started four games and made 14 tackles. The Jets are almost depleted at linebacker, but they're hoping Mosley and Jarrad Davis (ankle) are close to returning. Davis suffered a severe sprain in the preseason and hasn't played.