The franchise tag for Matt Cassel can come as early as Thursday. An ensuing trade can come as early as Feb. 28. Neither will likely happen that quickly, of course, but in both cases it’s just a matter of time. 

That’s not the question. 

The question is what everyone will get out of it.

For the Patriots, we at least have a general idea. Their return should be a first- or a second-round draft pick plus another selection in the middle rounds. Another possibility is an exchange of picks in the first round that would allow the Pats to move up from their current position at No. 24. There’s also a chance that the Pats could receive a veteran player in the mix, but those deals are rare. Most likely, it will be a combination of draft picks, one of which figures to be juicy.

The uncertainties are far greater for the Pats trade partner, and that’s because no one can predict what Cassel is going to be outside the comfy confines of Foxboro.

Is he a figment of our imagination, a product of great coaches, great receivers and an impeccable system? 

Or is he for real?

Put another way, is he Rob Johnson? Or is he Matt Hasselbeck? Is he going to be that unproven backup, like Johnson, who goes elsewhere for a big price and can’t deliver? Or is he the guy, like Hasselbeck, who proved to be very much worth the investment?

As usual, history is instructive. And it tells us Cassel is just as likely to fall on his face with his new team as he is to succeed. Sorry, Matt. Nothing personal. That’s just what the track record demonstrates.

Yes, there have certainly been some success stories, but more often than not, young, unproven backup quarterbacks who have been acquired to take over as a starter with a new franchise have ended up showing their new team exactly why they held the clipboard in the first place.

Here’s a look at a half-dozen cases from the past two decades that at least partly resemble Cassel’s, including both successes and the failures (listed in alphabetical order):

MARK BRUNELL

If the Cassel trade works out for his new team as well as Brunell did for Jacksonville, then that team should be thrilled. Brunell was Brett Favre’s backup for just one season in Green Bay in 1994, but he apparently showed enough in his limited action for the expansion Jags to tab him as a potential quarterback of the future, sending Green Bay third- and fifth-round picks in 1995. Brunell spent the next nine years in Jacksonville, making three Pro Bowls and leading the Jags to a pair of AFC title games. His record as a starter with the Jags was 63-54, which was stellar given their expansion status. While Brunell had an up-and-down ride the rest of his career, he proved to be very much worth the while for Jacksonville. 

Relating his case to Cassel’s, you’ve got to figure the Pats will do better in terms of draft pick compensation. Brunnell had no NFL starts on his resume when he was dealt and had thrown just 27 regular season passes for the Packers. Cassel, of course, has a full season of highly productive starts to his credit. 

On the other hand, Brunnell was considered a better product in college. He was a star early in his career at Washington, and only injuries derailed what was likely to be a high draft selection. After splitting time with Billy Joe Hobert late in his Washington career, Brunnell ended up going to Green Bay in the fifth round. Cassel, as we all know, barely played at USC despite enjoying good health and was taken by the Pats in the seventh round.

It will be interesting to see how teams gauge the experience factor when it comes to Cassel. He’s a unique case, a backup with far more starting NFL experience than college experience.

A.J. FEELEY

No one could figure out what the Dolphins were doing at the time, and nearly five years later, this move remains a mystery. It’s one of the many reasons why Bill Parcells is currently in charge down in South Florida.

Feeley was a third-stringer behind Donovan McNabb and Koy Detmer in Philadelphia when injuries to the top two guys in 2002 thrust him into game action. He responded with a very nice run, going 4-1 as a starter with six touchdowns, five interceptions and a 75.4 rating. Then, in 2003, he took a seat back on the bench.

That didn’t stop the Dolphins from sending the Eagles a second-round pick in 2004 and immediately inserting Feeley in the starting lineup. The Fish got what they paid for, as Feeley went 3-5 as a starter with 11 touchdowns, 15 interceptions and a brutal 61.7 rating. He returned to being a career backup quickly thereafter.

Feeley’s college resume, while certainly more complete than Cassel’s, was nothing to write home about, either. He was an early standout at Oregon, but like Cassel, he finished his college career as a backup to a future high draft pick, Joey Harrington. 

The Pats will certainly want to make the claim that if a guy like Feeley was worth a second-rounder, then Cassel is worth two firsts. Then again, it’s going to be hard to punish some other team for Miami’s stupidity.

MATT HASSELBECK

Another one that worked out for everyone involved. And given the fact it constituted insider trading, it should have. 

The Boston College product came into the pros with little fanfare, taken in the sixth round by the Packers in 1998. But Hasselbeck quickly established himself on the practice field, and while he never made an impact in the regular season, he put together some terrific preseasons for the Packers. He was so good, the folks in Green Bay started to call him Mr. August. Mike Holmgren, who knew Hasselbeck intimately from their time together in Wisconsin, then brought Hasselbeck to Seattle and hit pay dirt. Hasselbeck has compiled a 57-39 record as a starter with the Seahawks while making three Pro Bowls and leading his team to a Super Bowl appearance in 2005. 

The compensation sent back to the Packers was creative. Green Bay didn’t get a first- or a second-rounder outright, but they did flip picks with Seattle in the first round, moving from No. 17 up to No. 10. They also received a third-round pick from the Seahawks.

Don’t be surprised if the Pats consider a similar move. For example, San Francisco is currently sitting at No. 10 and should be in the market for a quarterback. You’d have to imagine that the opportunity to come out of the draft with a perceived franchise quarterback and still have the use of a first round pick would be appealing to the Niners, even though the Pats would surely ask for another second- or third-rounder in addition.

As for the Pats, the 10th pick has a nice ring to it. You still get a stud, but the rookie bonus dollars are more palatable. Remember, the Pats got Jerod Mayo at No. 10 last year. 

So what do you say, Patriots fans? Matt Cassel for Jerod Mayo and a second or a third? I’d take it.

ROB JOHNSON

The poster child for backups gone bad. The true embodiment of the Peter Principle.

Johnson was drafted by Jacksonville in the fourth round in 1995, the same year the Jags acquired Brunell, and never rose above bench-warmer status in three years. He started just one game for the Jags, although it turned out to be a doozy. In Week 1 in 1997, Johnson subbed for an injured Brunell and lit it up, going 20-of-24 for 294 yards and two touchdowns, in addition to 31 scramble yards and another score in a 28-27 win over Baltimore. The Bills obviously never forgot that game, because nearly two full seasons later, they sent the Jaguars first- and fourth-round picks to bring him up to Buffalo.

Buffalo regretted the move almost immediately, losing their first three games with Johnson behind center. Johnson went on to compile a 9-17 record as a Bills starter while making far more noise in his underhanded battle with Doug Flutie than he ever did on the field. The closest Johnson came to success came in the 1999 playoffs when he led the Bills to a late field goal in Tennessee only to be felled by the Music City Miracle. 

Again, if Johnson, who made one pro start and then was traded two years later, went for a first and a fourth, what is Cassel worth? Unfortunately for the Pats, they can’t really play that game. Plus, Johnson's value at the time was at least partly enhanced by what he did in college.

Unlike Cassel, Johnson was a stud at Southern Cal. He was a top Heisman candidate his senior year and left college owning most every school passing record in the books. That no doubt helped the Jags get that first-rounder in return. 

SCOTT MITCHELL

This signing was considered a shining example of the Lions' ineptness, but the truth is that there were a half-dozen teams lined up to make the same mistake with Dan Marino's backup.

Mitchell went to the Dolphins as a fourth-round pick out of Utah in 1990 and held the clipboard for Marino for the next three years. Then, in 1993, he got his break, starting seven games in place of the injured Hall of Famer and putting up respectable numbers (3-4 record as a starter, 12 touchdowns, eight interceptions, 84.2 rating).

Mitchell’s greatest accomplishment, however, was his timing. That offseason marked the beginning of the new CBA and the first true free agency year in NFL history-- and Mitchell's contract was up. Teams proceeded to wine and dine the big lefty. He was flown in private jets and escorted around cities in limos. Lions coach Wayne Fontes flew to Mitchell's home in Ft. Lauderdale and pitched him as if he were a college recruit. When Lions management also came up with the most money ($11 million over three years; how times have changed), Mitchell was on his way to Detroit. 

Today, Mitchell stands as one of the most hated figures in Lions history, even though his numbers don’t look so bad compared to where the Lions ended up this decade. Mitchell went 27-30 as a starter with a 79.2 quarterback rating over 57 games during the height of the Barry Sanders era. Mitchell twice helped the Lions reach the playoffs during his stay, but on both occasions he was brutal once he got there. He threw four interceptions in a wild card defeat at Philadelphia in 1995 and compiled a 48.4 rating in a wild card loss at Tampa Bay in 1997. 

The good news for the Lions is that Mitchell didn't cost them any draft picks; only money. It's something that fans in Detroit took no solace in. His tenure was considered an unmitigated failure.

MATT SCHAUB

The most recent example, and one that could prove to be another model for the Pats in terms of draft-pick compensation.

The Falcons originally drafted Schaub in the third round in 2004 thinking he’d be a steady and conventional backup-of-the-future for Michael Vick. Schaub mostly delivered on that billing, playing well in relief when called upon. And we probably saw him at his best in that role against the Pats in 2005, when he threw for 298 yards and three touchdowns and nearly engineered an upset of the two-time defending Super Bowl champions. Schaub would have been an ideal candidate to take over for Vick fulltime when the latter went to prison, but in a terrible bit of foresight, the Falcons traded Schaub away to Houston in 2007 before Vick's dog fighting charges played out. 

At least the Falcons got a good return, earning two second-round picks from the Texans (one in '07 and another in '08) in addition to a swap of first-rounders, which allowed Atlanta to move up from No. 10 to No. 8 overall. That’s another type of package you’d have to think the Pats would be pleased with. 

Schaub is another case of a guy who, while owning limited experience as a pro, was a blue-chip prospect in college, setting 22 school records at Virginia. The Texans were certainly able to tap into that game film in determining his value, something teams won't have the benefit of doing with Cassel.

As for whether Schaub was worth it to the Texans, the jury is still out on that one. He's missed 10 games the past two seasons due to injury and the Texans have just a 10-12 record with him as the starter. On the other hand, he's played well when given the time, throwing for 24 touchdowns, 19 interceptions and compiling a solid 90.3 quarterback rating over two seasons. Things are looking up in Houston, and if Schaub leads the Texans to the playoffs next season, then the trade will be considered a success. We'll have to see. 

CONCLUSION

If I had to predict what Cassel will be at his next stop, I’d put him in the Schaub category. That is, somewhere between the guys who flopped (Johnson, Feeley, Mitchell) and those who went on to be franchise guys (Brunnel, Hasselbeck).

A lot will have to do with location and the team around him, of course. If Scott Pioli brings him to Kansas City, for example, and builds a good team, Cassel will be fine. If he goes to Detroit and the Lions continue to puke themselves at the draft, he’s in trouble.

But no matter where he goes, I find it hard to imagine that he’ll be an outright bust. He’s learned too much under Belichick. His football intelligence is obviously high (you don’t improve as he did if it’s not), and I don’t know if you could say that about Feeley or Mitchell. Cassel has also displayed the right attitude throughout his Patriots tenure, whether it was as a backup, starter or pending franchise player, and Johnson obviously turned out to be just the opposite. Above all, Cassel proved he can take coaching, and if he lands with a good one there’s no reason to believe he won’t continue to develop. In other words, Cassel has the makeup to succeed. 

And whoever lands him will be getting a guy with far more substantive NFL experience than any of the examples listed above, even more than the two guys who worked out the best, Brunell and Hasselbeck. Cassel doesn’t have the collegiate pedigree, but you’ve got to figure that his 2008 resume trumps that. Cassel did the job when the lights were the brightest and the pressure was at its most intense. It should be a great jumping off point for his next place of employment.

As for Cassel’s physical abilities, they’re more than good enough. He can make most of the throws, and he runs as well as anyone. His single greatest improvement in 2008 was his pocket presence and mobility within the tackle box. Again, if that progression continues he should be a very good quarterback wherever he goes.

Then again, Scott Mitchell had a lot of upside, too.

Felger can be seen nightly on Comcast Sportsnet. He can be reached at mfelger@weei.com. His next mailbag will appear Feb. 12.