Theismann made the comments during a video interview with TMZ. Haskins, 22, was the No. 15 overall pick in the 2019 NFL Draft. The Ohio State product made his NFL debut in Week 4 against the New York Giants. Haskins threw three interceptions during the 24-3 loss.
"You can't start Dwayne Haskins against the New England Patriots," Theisman said. "I mean, it can't happen. It wouldn't be good for him, it wouldn't be good for the franchise, it wouldn't be good for football for crying out loud."
Theismann called Haskins "a young man with very little experience." He said he would have preferred that the Redskins keep Haskins on the bench. Theismann, 70, is the Redskins' all-time passing leader. The 1983 NFL MVP played for the franchise from 1974 through 1985.
The Redskins legend says nothing he saw in Week 4 showed him Haskins can't be an NFL quarterback. Theismann called the Redskins an "undisciplined football team," regardless of Haskins' play.
Haskins told reporters he had "a whole bunch of emotions" in his head when he was brought in to the game against the Giants to replace veteran Case Keenum.
He cited Patriots quarterback Tom Brady when asked about what would be special about playing New England in potentially his first start. The Patriots (4-0) own the best defense in the NFL, allowing a league-low 243 yards per game. The Patriots also have the second-best rush defense and pass defense, in terms of yards allowed.
"Maybe my first start being against Tom Brady," Haskins said. "That's pretty cool. He went to that team up north, so, there's not going to be any love on the field if I do play. It's exciting, we're home, good to be back and looking forward to it."
Redskins coach Jay Gruden said he will evaluate the team's quarterback situation when the team practices Wednesday. Keenum is also dealing with a foot injury. Washington has yet to announce their Week 5 starter.
"I think I'll figure that out, especially when I find out the true status of our quarterbacks that are banged up a little bit," Gruden said. "Obviously, Colt coming back from his leg injury, if he's 100 percent ready to go. Case, how he's doing with his foot -- he was in a boot after the game, precautionary reason.
"We'll see where they are. And then talking to Dwayne, seeing his progress. I'll make that determination. I think it will depend on the decision I make and then how that person performs on Thursday and Friday."
The Redskins host the Patriots at 1 p.m. EDT Sunday at FedEx Field in Landover, Md.