Instead, he believes he stirred up head coach Andy Reid.
Security guards asked Devlin, a 43-year-old from King of Prussia, Pa., to remove the jersey. He told Philadelphia radio station 97.5 The Fanatic he did so without complaint, adding the guard who asked him to remove the jersey said the request came from Reid.
A team spokesman denied that, saying that Reid was not aware of Devlin's presence and that the guards were acting to calm the commotion created when reporters crowded around the fan while practice was in session.
While many fans were happy to see McNabb go -- although he took the Eagles to five conference championship games, but didn't win a Super Bowl -- Devlin said he still thinks highly of McNabb.
He wore the McNabb jersey to a Phillies game Sunday, and said he got mixed reactions. On Wednesday, he got a sideline pass from a friend. Devlin said fans granted such access are given written instructions how to conduct themselves.
Devlin said cell phones and beverages are not permitted, but he was not made aware of restrictions on apparel of another team. A team spokesman confirmed that is not a set policy, just a preference.
"I just wanted to get reactions from the fan base, see who says what," Devlin said. "Maybe get in a healthy debate on whether Donovan McNabb was good or bad for this franchise."
But security intervened.
"I'm fine," he said. "Everybody was very cool, calm, professional and did not make a big deal about it. They asked me, and I figured I'm a guest at their facility, so why not make life easier for everybody?"
Devlin said the fans around him expressed surprise he was asked to strip down to the T-shirt he was wearing under the jersey.
"Nobody really thought I was really wrong," he said. "They asked me to do something, and I was more than happy to do it."
Devlin added he plans to wear the jersey when McNabb returns to Philadelphia on Oct. 3 to face his old team.
McNabb, on the other hand, must be wondering if he is back in Philadelphia.
On the first day of Redskins training camp, a heckler stood near the front of the crowd and criticized every bad pass, every bobbled ball and pined out loud for the return of departed quarterback Jason Campbell.
"Must have been a great catch," the fan yelled after McNabb completed one pass, "because it couldn't have been a good throw."
McNabb, a six-time Pro Bowler who spent 11 seasons with the Eagles, was traded in April to NFC East rival Washington.
As training camp continued, other fans might have felt that the heckler was on to something. McNabb seemed to be getting intercepted more than he should. He was throwing behind receivers, and earlier this week he unleashed a wounded duck downfield that was picked off easily by Carlos Rogers.
McNabb's performance could be simply a matter of him adjusting to new surroundings and a new offense. Or maybe fans are getting a glimpse of why the Eagles were willing to trade him after 11 seasons.
Naturally, McNabb and the Redskins chalk it up to the adjustment factor after only two weeks of training camp. All sides acknowledge, however, that there have been some growing pains.
"I think it's been different for him," offensive coordinator Kyle Shanahan said Wednesday. "He's been so comfortable in a situation for 11 years that he's never had to really grind out the system, because that [Eagles system] came natural to him with time. So it's been a little different for him knowing that he's really got to put in the work, and just the book -- just memorizing what we're doing, memorizing the verbiage -- so it's taken some time for him."
Coach Mike Shanahan noted that McNabb is essentially learning to speak a different language with different progressions and different footwork. Even a good student such as McNabb isn't going to master it right away.
"It's going to take some time where he feels it's second nature," Mike Shanahan said. "It usually takes a couple of years, even for a veteran."
Of course, no one is going to be patient enough to wait a couple of years. The season opener against the rival Dallas Cowboys is only 4½ weeks away. The first look at McNabb in a Redskins uniform in a game situation comes Friday night, when he'll likely get 12-15 snaps in the exhibition opener against the Buffalo Bills.
"It's a growing process," McNabb said. "We know that everything isn't going to be where we need to be for Dallas, but that's why we play the preseason, to kick the rust off a little bit and kind of get our timing and chemistry where we need to be."
Kyle Shanahan said some of the early miscues in camp might be beneficial in the long run.
"You almost sometimes want them to make some mistakes," Kyle Shanahan said, "because quarterbacks really don't remember what you want them to do until they mess it up. They get scarred by it and then they remember.
"Some of the new concepts he hasn't seen, and he has missed some of these throws and missed some of the reads, and I think it's good when that happens in practice, so he remembers them and remembers why it's not a good decision."
McNabb understands where his coach is coming from.
"Once you make a mistake and you realize what the mistake was, then you eliminate that," McNabb said. "That's for any player. Now if you kind of go through and you don't make a lot of mistakes, and then when you do, you don't have an answer for it? Then obviously you have to pull yourself back and try to find a solution. We've all made mistakes as these days continued on. We've all corrected them and found out what we did wrong."
So there's no need to panic. In fact, there's even time for laughs. McNabb was ready Wednesday when it was pointed out that he doesn't have as much hair as he used to.
"I'm an older guy now. I'm more mature. Responsible. Just really looking for that sexier look from the 30-and-over league -- for the ladies who are paying attention," he said.
McNabb is also vowing payback for a locker room prank played by tight end Chris Cooley, who had a youngster hide in McNabb's locker one day after practice. Cooley posted the video on the Internet of McNabb's priceless expression when the boy jumped out and surprised the quarterback.
"That's going to come back on all those guys who were responsible for that," McNabb said. "That's a dangerous thing, having someone jump out of your locker when you least expect it, but it'll come back."
Albert Haynesworth worked with the starters at nose tackle Wednesday, but only because Maake Kemoeatu was rested after needing an IV for dehydration Tuesday afternoon. Defensive coordinator Jim Haslett said Haynesworth needs "to clean up the technique" to play in the 3-4 defense. "We don't want him to spin. We don't want him to 'ole' blocks," Haslett said. "We want him to play with more power. The guy's a very, very powerful guy. I think he needs to use power in his game. I think that'll make him a better football player." ... DL Darrion Scott was carted off the field during Wednesday's practice in stifling heat and treated for dehydration. ... RB Clinton Portis returned after missing Tuesday's practice with a sore left groin. ... WR Malcolm Kelly (hamstring), RT Jammal Brown (hip), WR Mike Furrey (concussion), S Chris Horton (groin) and QB Richard Bartel (hamstring) won't play Friday. ... S LaRon Landry (toe) was limited in practice Wednesday but he will play.
Information from The Associated Press was used in this report.