FOXBOROUGH - This is how fast things can change in the NFL.

At this time last month, following the Patriots' 30-10 loss to the Chargers, media speculation buzzed that quarterback Matt Cassel could lose his starting job.

Three victories and one loss later, the speculation heading into last night's game against the Jets had turned to something completely different: How much could Cassel earn when he becomes an unrestricted free agent after the season?

Heading into last night's game, Cassel was 5-3 as a starter, but really it was 6-3 because he entered the season opener - a 17-10 win over the Chiefs - in the first quarter, when the game was scoreless.

Given that the quarterback position is the most important on the field, Cassel has shown he can lead a team to victory. What once seemed like a far-fetched thought is no longer.

When asked this week about becoming a starter in his free agent year, Cassel said, "All you can ask for in this game is an opportunity."

"The fact that I got the opportunity is definitely a blessing. Unfortunately, it came at the expense of the MVP of last season [Tom Brady]. Nobody ever wants to see that happen to such a great guy who's a close friend of yours. At the same time, it does happen in this game because it's a violent game. I feel very blessed and lucky to have the opportunity to get out there and play. That's all you can ask for as a young guy trying to make it in the league."

As for how much Cassel, 26, might command - assuming the Patriots don't place the franchise or transition tag on him, which seems unlikely - one former general manager said it's too early to tell.

"Clearly, he's improved throughout the year, but I think there is still a lot of Football to be played and you want to see how he plays over the rest of the season," said Charley Casserly, who is an NFL analyst for CBS.

Top backups, such as the Redskins' Todd Collins, make $3 million per season. Backups acquired with the purpose of making them starters have been paid as much as $8 million per season (Houston's Matt Schaub).

"All you need is one team to be interested, but with Matt Cassel, I don't think you can draw the comparison to Todd Collins or Matt Schaub," Casserly said. "The thing about Todd Collins is that he led the Redskins to the playoffs last year and made a lot of big plays throwing the Football.

"He showed what he could do when it was put on his shoulders to throw the ball. And with Schaub, even though he had limited playing time, you had more to go on from his time in college. So with both of those situations, I don't think you can parallel it to Cassel, except for the fact that all it takes is for one team to be interested."

Casserly believes Cassel's situation is so unique - he didn't play at Southern California - he can't recall another like it. That could play into how Cassel's unrestricted free agent situation unfolds.

"It's just the exposure you have to him," Casserly said. "A lot of times with young players, you have to go back and say, `What did you think of him in college?' What you thought of him in college, you combine that with what you see in the pros because you haven't seen a lot [in the NFL].

"In Cassel's case, this is all you got. Clearly, New England knows him better than anybody else, so if a New England staff member were to go to another team, it would be an interesting thing. They would have the best feel for him."

Entering last night, Cassel had completed 67 percent of his passes (179 of 267) for 1,800 yards. He had seven touchdown passes and seven interceptions, and had been sacked 29 times.

Some might question his performance because the Patriots have not asked him to do too much. Others have seen enough poise and command - as well as other quarterback struggles around the league (more than 50 quarterbacks have started at least one game) - to make a significant investment in him.

Regardless, Cassel had guaranteed one thing: He'll certainly be making more than the $520,000 he's earning this season.

Mike Reiss can be reached at mreiss@globe.com