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This winter I was speaking with Steve Clarkson, one of the top youth quarterback tutors in the country, about the state of the position. After decades of squiring teenage signal-callers from high school to college and the NFL, Clarkson believes the art of quarterbacking has reached a crossroads.

In short, the NFL's feeder system is providing mis-trained prospects. The spread offense might work at this level, but its quarterbacks can't survive it long-term and aren't equipped to adjust.

"It's pretty clear that quarterbacks in a spread at the NFL level take a beating," Clarkson said. "You can't last playing quarterback when you're exposed that way. ... Something has to give. Either you find a way to train them to play in the pocket, or the position is going to become situational in 10 years, because they're going to run out of them."

I can't help but reflect on that conversation amid news that the San Diego Chargers will put Oregon quarterback Marcus Mariota through a private workout next week. If they like what they see, or so goes the informed speculation, they would consider trading starter Philip Rivers to the Tennessee Titans to select Mariota with the No. 2 overall pick in the April 30 draft.

That tack seems irresponsibly proactive at this juncture in NFL history, with the supply of quality pocket passers at a low point. If Clarkson is right, and I think what he said makes a lot of sense, the Chargers should ride Rivers until his arm falls off.

Mariota spent his time at Oregon playing in a scheme that appears untenable at the NFL level. The most relevant test case is Robert Griffin III's ongoing struggles with the Washington Redskins.

At some point, the league will figure out how to traverse the gap created by the spread's proliferation. Maybe it means a dedicated developmental league. Perhaps teams will use multiple spread quarterbacks in a game. Until then, however, it seems crazy to move on from a top-10 player at the position -- even one who is 33, nearing the end of his contract and perhaps unwilling to accompany the Chargers on a possible move to Los Angeles -- in favor of a player whose pocket skills are nothing more than a projection.

Check out the chart accompanying this post. The top 10 quarterbacks in the NFL last season, as measured by Total Quarterback Rating, were all traditional passers with an average age of 33. Only two, Joe Flacco and Matt Ryan, were under 30 when the season ended. (Both were 29.)

The continued success of Peyton Manning (38), Tom Brady (37) and Drew Brees (35), among others, suggests a precedent for Rivers, barring some kind of health issue we're not aware of. In today's game, there is fair reason to think a 33-year-old quarterback can continue playing for five or more years provided his skills match a scheme that protects him.

Would you give up five more years of Rivers at a relatively high level in exchange for the potential of 10 years from Mariota, which could of course also mean a washout in three years? To me, that's what the Chargers should be asking themselves -- if in fact they're considering the scenario at all.

Mariota would be an upgrade for many NFL teams, and this is not to say that young quarterbacks can't succeed in the NFL. Andrew Luck (25) ranked No. 11 in QBR last season and Russell Wilson (26) was No. 12. But neither of them were spread quarterbacks when they were drafted. They were pocket passers who also have mobility.

The Chargers have on their roster a quarterback who could take a generation or more to replace, let alone upgrade from. Given the game's current landscape, why rush it?