This is going to pain Troy Tulowitzki more than a trip to the disabled list, but the best shortstop in the game needs to consider a new job.

Tulowitzki is a third baseman waiting to happen. Not this season. But soon. Sooner than he or the Rockies dare think.

Alex Rodriguez, one of the top five home-run hitters in major-league baseball history, switched from shortstop to third base at age 28. Tulowitzki will celebrate his 28th birthday in October.

His body is telling Tulowitzki that the move is inevitable. What’s more, the transition could also be extremely beneficial to the Rockies. For the worst part of a decade, whenever Vinny Castilla was not manning the position, this franchise’s third baseman has been straight out of an Abbott and Costello routine: I Don’t Know.

Just as the Rockies were awakening from a spring-long funk, Tulowitzki landed Thursday on the 15-day disabled list with a strained groin.

If there’s any legitimate criticism of his brilliant career, it’s bad luck with injury. Tulowitzki was limited to 101 games in 2008 and 122 games in 2010. He plays the game like there’s no tomorrow. We love the attitude but hate it when he’s on the shelf.

Shortstops are not supposed to be built like Popeye. While he can chase down a grounder in the hole with the artistry of a Mikhail Baryshnikov pirouette, Tulowitzki could live in a yoga studio and have trouble keeping his tightly wound muscles loose.

The face of the franchise needs to have his bat in the everyday lineup. Tulowitzki hits in the heart of the order and is the heartbeat of the Colorado offense.

Pencil him in at third base for 155 games per season and Rockies manager Jim Tracy could count on Tulo producing 30 home runs and 100 RBIs per season until his contract expires in 2020.

Oh, there will be loud objections to messing with a Gold Glove shortstop. The Rockies would have to drag Tulo kicking and screaming to the hot corner. The mere suggestion of this idea might hurt Tulowitzki so deeply I’m not sure he will even be able to speak to me for at least 15 days.

If you locked all the general managers in a room and asked them to start their big-league teams from scratch, here’s betting Tulowitzki would be right there with Los Angeles Dodgers outfielder Matt Kemp and Detroit starting pitcher Justin Verlander among the top five players taken in the draft. Being the best shortstop in the game contributes heavily to Tulo’s value. He can’t be the MVP of the league from the disabled list, though.

Shortstop is in his DNA. But DNP appears too frequently next to his name. Too often, Tulowitzki does not play because he’s hurt. For all the homers that Carlos Gonzalez bashes, the Rockies need Tulo to set the tone.

This is not to suggest third base is a day at the beach. For all the hot smashes faced, maybe a goalie mask should be included in every third baseman’s equipment bag.

In Coors Field, where innings can go on forever, playing shortstop is serious work that grinds on the body and mind, especially for a player as relentless as Tulowitzki.

While he doesn’t want to think about it now, Tulowitzki will be a third baseman at some point in his career. The Rockies could wait five years down the road, but why let the heavy workload of shortstop accelerate diminishing returns in offensive production over time?

How many years away is Colorado from being a legitimate World Series contender?

As is so often the case with this franchise, it’s June and the Rockies are already playing for the future.

The future of Tulowitzki is at third base.

Mark Kiszla: 303-954-1053 or mkiszla@denverpost.com