EAST RUTHERFORD, N.J. -- With one slip of the tongue, Geno Smith turned a bad day into a really bad day. After another poor performance, resulting in occasional chants of "We Want Vick!" at MetLife Stadium, Smith walked off the field Sunday -- clearly angry -- and violated one of the 10 commandments of NFL quarterbacking: Thou shalt not let the fans get inside your head.

"F--- you!" Smith yelled at a heckler behind the New York Jets' bench after an ugly 24-17 loss to the Detroit Lions -- the Jets' third straight defeat.

The brief exchange was caught on camera by WCBS 2 New York, and it shows Smith glaring at the fan, pausing a moment and shouting the profanity with conviction. There was nothing flippant about it.

We might have witnessed the beginning of the end of Smith as the Jets' starting quarterback.

It wasn't just the unfortunate outburst; it was everything that unfolded. The supposedly improved Smith continued to regress, committing two turnovers and missing a handful of open receivers. He fed the blood-thirsty crowd, which started chanting for Michael Vick during a stretch of five consecutive three-and-out possessions in the first half. It got louder in the fourth quarter, when Smith was intercepted.

It's one thing when a gladiator is defeated by the lions -- or, in this case, the Lions. It's quite another situation when he's affected by the coliseum's angry mob. Smith let it get to him -- the bad day, the swirling quarterback controversy, everything. During his postgame apology, he said it was only "one guy" in the crowd, but that doesn't matter. Smith showed cracks, stripping away perhaps his greatest attribute -- his thick skin.

Smith is known for an even-keeled demeanor, which he demonstrated during a wildly inconsistent rookie season. But Sunday's outburst showed a different side. A starting quarterback can't have rabbit ears; it's not a good look. You don't pick fights with the paying customers. It shows immaturity and a lack of poise. For all his mistakes, Mark Sanchez never lashed out at a fan.

"It's part of my learning process," Smith said. "I have to get better with that. I have to let that stuff roll off my back. But today I didn't do well with that."

Smith received a vote of confidence from Jets coach Rex Ryan, who said he's not considering a change. It's the right call; Smith should get at least another start to right himself and the offense. At this point, benching Smith would be a panic move for an organization that still believes he can be the franchise quarterback, but let's be clear: It has to be a short leash. The margin for error is almost gone. The chances of a 1-3 team making the playoffs are 14.5 percent, according to ESPN Stats & Information research.

That the Jets are going on the road, facing the San Diego Chargers, is a plus for Smith. To paraphrase the slogan in an airline commercial, he needs to get away.

Ryan said he never considered switching to Vick, although I'm not sure I'm buying that. I think Smith bought himself the rest of the game by opening the second half with a 74-yard touchdown drive that ended with his 11-yard scoring pass to Eric Decker. But it went downhill from there, starting with Smith's interception and a strip-sack on back-to-back possessions. He has seven turnovers in four games, and his passer rating has dropped to 77.0.

"No, I'm not going to replace him," Ryan said. "I feel good about Geno. I think he will get it turned [around]. He's a tough, resilient young man. ... I think he has the tools to be really good. In my opinion, it's not a question of if it's going to happen, but a question of when he will be that kind of guy. I think he's a good quarterback. I think he has a chance to really be something one day."

Part of the problem is a trust issue. After last week's loss, offensive coordinator Marty Mornhinweg chided himself for putting "too much on his plate." On Sunday, Mornhinweg's cleaned Smith's plate, leaving only a couple of crumbs. It was an ultra-conservative game plan, starting with 10 runs on the first 13 plays. It led to an early field goal, but then came the deep freeze. Smith completed 17 of 33 passes for 209 yards and, frankly, he was worse than the stats indicate.

"I have to make sure I right the ship and get this team going," Smith said.

Right now, the team is headed toward an iceberg.