Tom Brady's had a storied career, but what if he never gets back?

Since laughing at Plaxico Burress, Tom Brady has played three full NFL games and won one. He has seen the Giants hold his Patriots to 14 points, three below Burress' prediction, and watched David Tyree make a preposterous catch to set up Burress's game-winner. In last season's opener, he tore up his knee and was lost for the year.

He has had a miserable 21 months (except, you know, for that day when he married a supermodel.)

Worse, last week the Patriots lost the kind of game they always win. It was in New York, where they always win, against the Jets, who never win, and after first-year Jets coach Rex Ryan and safety Kerry Rhodes both mouthed off before the game. Normally when people publicly question the Patriots, they are calling a timeout by the third quarter to say uncle.

This time, the Patriots lost, 16-9. They didn't even score a touchdown. Brady's quarterback rating was 53.1.

Brady is still recovering from major knee surgery. Like most people, I expect him to play at a Pro Bowl level again, probably very soon. But I keep thinking: What if he never gets back?

What if he finishes his career without winning another Super Bowl? What if the Patriots never dominate again? Would Brady be considered one of the alltime best?

It seems crazy. Brady looks like a Hall of Famer. The Super Bowl doesn't feel complete without him. He is one of the great winners in NFL history. But so was Troy Aikman. In January 1996, at the age of 29, Aikman won his third Super Bowl with the Cowboys. Everyone knew his goal was to win more Super Bowls than any other quarterback in history. Aikman needed only one more to tie Joe Montana and Terry Bradshaw.

Aikman only won one more postseason game in his career. He retired at age 34, after a series of concussions left his brain so scrambled he had to become a member of the media.

Yes, I know. Aikman played the last few years for a dysfunctional Cowboys franchise and unimpressive coaches (Barry Switzer, Chan Gailey and Dave Campo). Brady gets to play for Bill Belichick.

Belichick is a mastermind, one of the great coaches in NFL history. But so was Don Shula. From 1968 to 1973, Shula had a Belichick-like run: four Super Bowl appearances in seven years, including Super Bowl wins after the 1972 and 1973 seasons.

Shula coached 22 more years after that and only had two losing seasons. He made it back to the Super Bowl twice. He had one of the great quarterbacks ever, Dan Marino. But he never won another Super Bowl.

I think I know why. It is a complicated answer, and it took me many years of watching football to come up with it, but here goes: Winning the Super Bowl is hard.

It is fair to wonder if Tom Brady will ever play in another Super Bowl, because most quarterbacks in the NFL will never play in another Super Bowl.

At 32, Brady has already compiled one of the best NFL résumés ever. (The employees at his local Kinko's are VERY impressed.) He may win another Super Bowl, even this year.

But the point is, it can all slip away very quickly. Twenty-one months ago Brady looked as if he would keep on winning forever. But in sports, forever is a punch line. The landscape changes week to week. If Brady and the Patriots lose to Matt Ryan and the Falcons at home on Sunday, you can expect a slew of stories about a changing of the guard.

But know this: Brady is listening to these questions, just as he listened to Burress' prediction, just as he heard people in his University of Michigan days say backup Drew Henson was more talented, just as he heard others say he'd never play in the NFL. History says it is unwise to doubt Tom Brady. He has overcome plenty of obstacles and beaten the odds before.

This, I think, is the biggest difference between Brady and Peyton Manning. Since Manning's youth, people expected him to be a star quarterback, first because of his bloodlines and then because of his obvious talent. He was the top-rated recruit in his high school class. He started at Tennessee as a true freshman. By his third year on campus, Manning was already projected as the No. 1 pick in the draft whenever he came out.

Brady, on the other hand, kept getting pushed off the mountain. As a young player at Michigan, he walked into coach Lloyd Carr's office and demanded playing time, and he still didn't get it. Brian Griese played instead. Brady was stuck at third-string. (Carr's response in that meeting, which Brady has taken to heart ever since: You know, Tommy, you've gotta worry about yourself.)

Brady did not start for Michigan until his fourth year. In his fifth, Carr had to defend his decision to split time between Brady and Henson by saying that Brady will play in the NFL. Nobody outside of Brady's family ever said that before. The Patriots took a flier on him in the sixth round, at the urging of their quarterbacks coach, Dick Rehbein.

I think this helps explain why Brady has fared better than Manning in the most crucial situations. There is no way to prove this, of course. But Manning has been conditioned to think wild success is the norm for him. Naturally, when failure seems likely, it can be a little jarring.

But when Brady's team trails in the final two minutes, well, hey, that's just another chance for him to do something everybody figured he couldn't do. He thrives on doubt. He may yet turn today's questions into answers that just add to the legend.

He succeeded after the loss of Rehbein (who died in 2001 of a heart ailment), which devastated him. He made Super Bowls with three almost completely different sets of receivers. He watched expert play-caller Charlie Weis leave for Notre Dame, then went 16-0 without him.

Tom Brady might win as much as he has before, as much as anybody in the NFL ever has. But don't assume it. The sports world spins faster than we realize.

Just ask Plaxico.