Over the past few months, during what we’ll refer to as  the “Summer of Favre,” news on Brett Favre of the New York Jets (man, that sounds weird) was omnipresent. The powers-that-be in Green Bay rolled the dice by slamming the door in his face after hearing he wanted to return to the gridiron. A few grueling weeks later, we got our first look at Favre in a Jets jersey – a shocking sight.

It wasn’t the first time, of course, that a football legend changed teams in his twilight. That’s how it happened with Johnny Unitas, too. In 1972, the Baltimore Colts deemed him too old to play anymore; he wanted to continue. So it was a sad day when they peddled their longtime star to the Chargers. My dad had been a longtime Colts follower, but he never felt the same about the franchise after they said “happy trails” to Unitas.

I was in attendance at the final game Unitas started. It was a cold October Sunday in Pittsburgh in 1973, and we watched with excitement when the Chargers, led by their 40-year-old quarterback, took the field. Alas, Johnny U couldn’t have had a tougher opponent that day; this was the Steel Curtain, a defense loaded with future Hall of Famers.

Sure enough, the Steelers knocked Unitas around pretty good, and the game got downright ugly: It was Pittsburgh 38, San Diego 0, at halftime. The NFL’s most storied player completed just 2 of 9 passes for 19 yards and looked hobbled while trying to escape ferocious pressure by the likes of Mean Joe Greene. I remember feeling bad for Johnny U, but also for my dad. He had hoped to see some old Unitas magic that afternoon, but No. 19 was a far cry from the man whose daring throws and pinpoint accuracy had been lighting up scoreboards since 1956.

When the second half started, the Chargers mercifully trotted out a new QB: 22-year-old Dan Fouts. Johnny U would never start another game, and would throw only one more pass that season.

By the time the sports memorabilia hobby was soaring in the 1990s, Unitas was appearing at card shows, always with healthy lines of fans paying $40, $50, $80 for his autograph, virtually always on a Colts item. I sat with Unitas at two different Tuff Stuff shows in the 1990s and didn’t see any Chargers memorabilia land at his table. That doesn’t mean it doesn’t exist; it’s just rare.

But look hard enough and you’ll find oddities like a powder-blue San Diego jersey with “Unitas” on the back (I recently saw an unsigned one on eBay for $56) and the occasional signed photo of Unitas in action as a Charger (around $125, same as a Colts photo). Recently, I spotted a Unitas-signed San Diego mini-helmet offered at $250.

Such unusual pieces would make the basis for a great collecting theme: NFL players in the “wrong” uniform. Besides Unitas, you could look for these stars:

• Joe Montana as a Chief: In the area of game-worn jerseys, Montana-signed (No. 16) 49ers jerseys can sell for $3,000-$10,000 and up. His No. 19 Chiefs jersey is harder to find but can actually sell for less. Collectors want Montana paired with his original team, so the demand for Chiefs-related items is not as great.
• Joe Namath as a Ram: Broadway Joe played in just four games with the L.A. Rams in 1977 after a dozen years with the Jets. Next time you’re at a show, try to find a Namath-signed Rams mini-helmet or photo. His signature appears mainly on Jets-related items.
• Jim Taylor as a Saint: The Green Bay great finished his career with a tough season in New Orleans in 1967 (130 carries, 390 yards). One neat find from that year: a colorful Sports Illustrated cover he shared with quarterback Gary Cuozzo (unsigned copies go for around $10; autographed: $35-$60). The best Taylor mementos, however, reflect Packers green and gold.
• Franco Harris as a Seahawk: It’s hard enough to think of contemporary halfbacks like Thurman Thomas as a Dolphin (he played for Miami in 2000 after 12 years with Buffalo) and Emmitt Smith as a Cardinal (he spent 2003 and 2004 with Arizona after 13 years with Dallas). But how about Franco Harris? After a storied career in Pittsburgh, he moved to Seattle for one last year in 1984, and it just didn’t seem right.

All of these players, along with such Hall of Famers as John Mackey the Charger, Lance Alworth the Cowboy and Don Maynard the Cardinal, serve as reminders of an unpleasant inevitability: The day always comes when management decides, rightfully or not, to go “out with the old, in with the new.” At the same time, these out-of-place legends combine to give us a unique collecting angle.