Free agent running back Thomas Jones signed with the Kansas City Chiefs Tuesday in a move I don’t completely understand.

Jones, who played 2009 at 31 years old, is coming off of the two most productive seasons of his career during which he’s run for a total of 2,714 yards and 27 touchdowns while adding two more scores through the air in 2008.

Despite the fact that he appears to be getting stronger with age, he was clearly being usurped by Shonn Greene during the New York Jets’ playoff run last season. And the Jets cut Jones in early March, though by some accounts they wanted to sign him back after avoiding paying him a $3 million roster bonus.

His teammates reportedly wanted him back, though in the end Greene showed a speed-power combo last year that as the season wore on Jones wasn’t able to match.

Thing is, by signing with the Chiefs, Jones joins a team where he’ll be competing for carries … with a younger, shiftier back that showed great potential during the 2009 season.

Sound familiar?

Jamaal Charles looks nothing like Shonn Greene. The Chiefs’ sudden superstar is 30 pounds lighter than Greene and not quite the moose behind the tackles that the Jets appear to have in the 2009 draft choice from Iowa. But Charles opened eyes after Kansas City jettisoned Larry Johnson by finishing the season with 1,120 yards on just 190 carries. Charles also showed promise at the stripe, scoring seven times on the ground.

So, while there’s a role to be had for Jones, he’s likely to end up on the short end of a timeshare in Missouri much like he probably was destined to do in New York.

And he’ll be doing so on a rebuilding team rather than one that looks like it should be one of the favorites to represent the AFC in the Super Bowl in 2010.

And he’ll be doing so on a team with a much, much less skilled offensive line – the Jets’ blockers are arguably the best in the NFL while the Chiefs front wall … well, isn’t.

Don’t get me wrong – I like some of the young guys the Chiefs have brought in, including Charles. And Jones does become part of a two-headed monster rather than a three-headed one, which the Jets’ running game was likely to become if Jones had re-signed and when Leon Washington returns from his broken leg.

But at this stage in Jones’ career, if he’s not going to be the undisputed number one running option, why wouldn’t he choose to be a rotation guy with a role on a good-to-great team over a similar role on one that has only won 10 games the last three seasons and is a ways away from being a real contender?

Maybe there’s some pride involved. I can only imagine how frustrating it would be for a player to put forth his best season ever only to see his role reduced late in the season. But the situation in New York just seemed to me like a much better fit in the short-term. And at 32, running backs in the NFL are running on borrowed time.