The Patriots’ Matt Cassel, celebrating his touchdown run against the Dolphins last Sunday, likely will be playing in a different system next season.

The Providence Journal / Bob Breidenbach

FOXBORO — As should be obvious to anyone who has paid any attention to the Patriots this season, Matt Cassel clearly is better than Tom Brady.

As a runner, that is.

Not as a passer.

“He has had some good results with running the football,” Pats offensive coordinator Josh McDaniels said.

He has, indeed — 53 carries for 199 yards (his 3.8 yards-per-carry average is half a yard better than Laurence Maroney’s when that former first-round pick was placed on I.R.) and two touchdowns, the latest an eight-yard scramble against the Dolphins last Sunday in Miami.

“Matt made the smart play there,” McDaniels said. “They were in a coverage mode and were really trying to make sure the receivers were covered. We were in an empty backfield, so most of their attention was being paid to the receivers. He made a good choice on it and scored.”

Cassel has been making better and better choices, week after week, both running and throwing the football, and the Patriots have been scoring more and more points — 31 in the overtime loss to the Jets, followed by a season-high 48 at Miami.

He has passed for more than 400 yards in back-to-back games — only the fifth quarterback in NFL history to do so. Brady, by contrast, has thrown for more than 400 yards just once in his entire career.

The 530 yards the Patriots racked up against the Dolphins last week is the second-highest total in franchise history, trailing only the 597 that, with Steve Grogan at QB, the Pats amassed in a 56-3 rout of the Jets in 1979.

Cassel’s aerial circus act in Miami earned him AFC Offensive Player of the Week honors for the second time this season. The first was after the 41-7 blasting of the Broncos.

So perhaps it shouldn’t be surprising that some fans are wondering if maybe — just maybe — the Patriots would be wiser to sign Cassel to a long-term contract and try to trade Brady, who is five years older and coming off major knee surgery.

While not surprising, it’s not smart.

It’s foolish.

How soon they forget.

Must New England fans be reminded that it was only last year that Brady brought the Patriots within two minutes of just the second perfect season in NFL history, throwing for a league-record 50 touchdowns?

That, in his seven seasons as starting QB, Brady has taken the Pats to four Super Bowls, won three, and been MVP in two? That he led them to six division titles? That, in 2006, he got them to the AFC Championship Game with a receiving corps featuring flotsam and jetsam, not Randy Moss and Wes Welker?

Lest we forget, if the playoffs were to begin today, the Patriots, for the first time in six seasons, wouldn’t be participating.

Cassel is deserving of any and all praise people want to heap upon him. He has played better than just about anyone — including, if they chose to reveal such things, probably even McDaniels and head coach Bill Belichick — expected.

He looks comfortable — although that could change this afternoon, with the Steelers’ top-ranked defense coming after him — and in control. He has been throwing the ball well, making good decisions. He moves well in the pocket, and also knows when to break out of it and either throw on the run or take off with the ball himself.

After years on the sidelines — including his entire college career at Southern Cal, where he sat behind Heisman Trophy winners Carson Palmer and Matt Leinart — Cassel has made the most of his opportunity to finally play and, in the process, has put himself in position to make some serious money. With quality quarterbacking in short supply, teams will be bidding feverishly for his services when his contract expires after this season.

Unless Brady’s rehab is going much worse than anyone in the organization is letting on, there is no chance the Patriots will be one of those teams.

First of all, there’s no way they can afford to pay both Brady and Cassel. If the Pats were to put the franchise tag on Cassel for 2009, they’d have to pay him a salary equivalent to the average of the five highest-paid QBs, a move that would be financially prohibitive under the salary cap. So he’ll almost certainly be playing somewhere else next season.

Somewhere with a different system — one that hasn’t been honed to near-perfection, designed and coached by a future Hall of Famer like Belichick.

Somewhere where he’s not likely to have a future Hall of Fame receiver, like Moss, or as talented a possession receiver as Welker, or a highly reliable veteran such as Kevin Faulk catching the ball out of the backfield.

Somewhere where he won’t be operating behind an experienced offensive line that has been together for several seasons and features two Pro Bowl selections in left tackle Matt Light and left guard Logan Mankins.

While it’s selling Cassel short to say he’s simply a product of the system — just because a NASCAR driver has a hot car, that doesn’t mean he can handle it at high speeds on the racetrack — there’s no question that he has benefited tremendously from the players and coaches around him in New England.

Whether he looks as good next year, with different personnel, different coaching, different plays, and the high expectations that come with a big contract, will be interesting to see.

But people who see Cassel as a better quarterback than Brady don’t know what they’re looking at.

jdonald@projo.com