Matt Cassel has seized an opportunity to lead the Pats’ offense. On Sunday, he became only the fifth player in NFL history to throw for more than 400 yards in back-to-back games.

The Providence Journal / Bob Breidenbach

He has become the frog who dreamed of being a king and then became one.

He is every kid who ever sat on the bench and dreamed his dreams, while all the cheers went to someone else.

He is the kid who finally got his chance and proved everyone wrong.

He is Matt Cassel, the latest reminder that just when we think we know all about sports, something happens to make us realize we don’t, the latest reminder that sports are never better than when some kid comes out of nowhere to write his own improbable script.

Could anyone make this up?

Not really.

His story seems to jump off the pages of adolescent fiction, a football rags-to-riches saga that no one over the age of 12 or so would believe. This guy who never started a game since high school, a guy who looked so bad in the exhibition games that there was speculation that he might even be cut, this no-name guy who Sunday became only the fifth player in NFL history to throw for more than 400 yards in back-to-back games.

Tom Brady?

Who is Tom Brady?

Just kidding.

But the parallels are strikingly familiar. Two young quarterbacks who got their chances because of injuries. Two young quarterbacks who have come out of nowhere. Two young quarterbacks who almost immediately have become better than any of us had a right to expect.

And if Brady’s story is stranger than fiction, the sixth-round draft choice who went on to win three Super Bowls, become an MVP, stare out from magazine covers, and win the girl, too, Cassel’s is still a work in progress, however improbable it already is.

And the best thing about it?

It seems to get better every week.

Remember in the beginning when the word was he was being asked to only manage the game, not win it? Remember in the beginning when he often had that deer-in-the-headlights look, as if the game was all happening a little too quickly for him, like trying to watch a movie that’s been speeded up?

All that’s now gone.

Throwing for more than 400 yards two weeks in a row will do that. Showing the ability to run when things are breaking down will do that. Being able to put 48 points on the board will do that.

And, yes, he has a great receiver in Randy Moss, and a very good one in Wes Welker. Yes, he benefits from an offense that is multidimensional, and enables him to throw a lot of short passes that pad the stats. Yet there’s no one who could have thought back there in early September that Cassel was going to become what he is today.

Probably not even Cassel.

He was on Boston sports-talk radio station WEEI yesterday morning saying how the first thing he had to do was convince the other guys in the huddle to believe in him. One suspects that was no easy task. Why should they have any faith in him? They just had Brady and now they had Cassel? Please.

So Cassel’s first task was to prove to his teammates that he could play, prove that their season wasn’t just about what-might-have-beens, over by the time the leaves started to change. That didn’t happen overnight, of course. Remember the game in mid-October when they got pasted by the Chargers, 30-10, the game in which Cassel had a meltdown on a first-and-goal from the two?

Where are you, Tom Brady, the Patriots turn their lonely eyes to you.

But he has now come into his own, as though each week has become another coming-out party. It began with putting 41 points on the board against the Broncos on Monday Night Football, the game that not only began to turn the Pats’ season around, but also became the symbolic moment when Cassel began to change the perception of him, throwing for three touchdowns.

The next week he brought the Pats back from a fourth-quarter deficit to beat the Rams at Gillette Stadium.

And somewhere along the way he changed everyone’s perception. His teammates. The coaching staff’s. The rest of us.

To the point that now we expect him to be good, expect him to make good decisions and get the ball to people, expect him to be able to lead this team. To the point that he’s now putting up amazing numbers in a league where young, untested quarterbacks are not supposed to be able to do that.

And who would have believed that back in mid-September?

For this already has been an amazing season, regardless of how it turns out, and that is because of Cassel, who has come out of nowhere to be one of the best stories of this NFL season.

The frog who dreamed about being a prince and became one.

Every kid who ever sat on the bench and dreamed his dreams, while all the cheers went to someone else.

The kid who finally got his chance and proved everyone wrong.

Matt Cassel, the latest reminder that sports are never better than when someone comes out of nowhere and writes an improbable script.

breynold@projo.com