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04/21/11 10:00 AM ET

Mauer too valuable as a catcher

Offensive prowess while behind the plate isn't worth giving up

Joe Mauer's birthday was on Tuesday. He turned 28. Not 48, as you might suspect from the attention his beleaguered body is getting these days, but 28.

By the time the Twins' contractual rights to Mauer run out, he'll be 35. The investment Minnesota made in him is tremendous. In fact, it is the largest investment any team has ever made in any catcher. The eight-year, $184 million contract was the product of two indisputable facts:

1. Mauer is a Twins Cities product and the face of the franchise.

2. Mauer is the most productive catcher in the game.

Fact No. 1 isn't changing, unless there's some birth-certificate controversy of which I'm not aware.

But fact No. 2 has become a talking point because of Mauer's lengthy list of leg injuries, including his current stint on the disabled list with the mysterious diagnosis of "bilateral leg weakness."

The Twins have said that his current condition is the result of a viral infection and not a more serious, structural concern, though even Mauer has expressed doubt that the two issues are not related.

All this has served to augment the argument -- articulated by MLB.com colleague Alden Gonzalez -- that for the good of his team, for the good of his health, and, yes, for the good of his contract, Mauer needs to make a move. To right field. To first base. To DH. Anywhere that spares him from the wear and tear of catching.

A move will almost certainly come to fruition at some point in the next eight seasons. But now -- and for that matter, the next few seasons -- is not the time.

Look, I don't have access to Mauer's medicals, so I can't claim to know more about his condition than I do. I would say that the theory articulated by Mauer himself -- that the leg weakness is partly attributable to last fall's arthroscopic surgery on his left knee, therefore affecting his offseason workout regimen -- appears plausible. If that's the case, one would imagine that a few weeks on the shelf to build up strength would get him ready to resume his role behind the plate, much in the same way he returned from joint issues that held him back the first month of what became an MVP season in 2009.

Again, though, without access to the medicals, all we can do is speculate. And let's keep this in mind: The belief that all of Mauer's medical issues over the years are directly tied to catching is purely speculation.

All I know for sure is that Mauer's greatest offensive value to his team is behind the plate, not anywhere else in the field. Aside from that insane '09 season, in which his .365 average, .444 on-base percentage and .587 slugging percentage all led the American League, the nobility of his numbers rests in the fact that they come from a position that rarely produces with such potency.

Mauer's career .885 OPS would be respectable at any position, but at a corner infield or outfield spot, it loses its "elite" luster. Though Mauer is athletic, we're not talking about a Craig Biggio here. He can't be plugged into any other middle-of-the-diamond position.

That is the primary reason why the Twins should (and will) be patient with Mauer's medical issues and continue to pencil him in behind the plate, once he's physically deemed good to go.

But there's another point that we must usher into the argument: Mauer is an excellent defensive catcher, and not just because he has a few of those sham awards known as the Gold Glove.

Though no defensive metric is perfect, some seem a more fair gauge than others. Baseball-Reference.com has a "Total Zone" fielding runs above average stat that considers stolen bases allowed, caught stealing, errors, pickoffs, passed balls and wild pitches, compares those numbers with the league averages and then converts them to a runs-above-average statistic.

Mauer's career Total Zone mark of 44 ranks 23rd all-time, according to the site. If we take his Total Zone per 1,000 innings caught, his 7.0 mark ranks fourth among active catchers -- trailing only Yadier Molina (11.3), Henry Blanco (8.7) and Ivan Rodriguez (8.1) -- and ties him with Gerald Laird and Mike LaValliere for 14th all-time, slightly ahead of Johnny Bench (6.7).

Combine that metric with our anecdotal knowledge of what Mauer brings to the position, in terms of how he handles the pitching staff, and we have greater evidence that he belongs behind the plate.

Now, does that mean the Twins shouldn't consider lightening his catching load to prolong his usefulness at the position? Of course not.

We can turn to an AL Central foe to see how the Twins can best handle this situation. Victor Martinez was 27 in 2006, when the Indians began working him in at first base. Martinez played 133 games at catcher and 22 at first that year, which would seem to be a nice balance between the two and a precedent the Twins should certainly consider following when Mauer returns.

Of course, the Twins have quite a logistical issue at hand, one that only serves to lend further credence to my belief that now is not the time to make a move with Mauer. Jim Thome is set at DH for this year, Michael Cuddyer and Jason Kubel man right field, and, above all else, Justin Morneau is entrenched at first base through 2013, provided he remains healthy. So it's not as if you can simply slot Mauer into a new position, give Drew Butera the everyday catching duties and be done with it. And let's also keep in mind that Mauer hasn't logged so much as a single professional inning at any position other than catcher or DH since 2003.

Mauer, listed at 6-foot-5 and 235 pounds, is a big dude, and that inevitably leads to concerns about how his body will tolerate catching long-term. Those concerns have been uttered ever since he was drafted by the Twins, and they gained considerable traction when he signed that gargantuan deal.

But the deal is done, and, for the Twins, there's no going back. The day Mauer moves to another position permanently is the day his value takes a dive, the day the premium of his contract is lost.

In 1974, Carlton Fisk tore several ligaments in his knee and was told he'd never play again. He went on to squat behind the plate for another 15,654 innings. Nobody's claiming Mauer is going to have quite that much endurance, but the Twins need to ride him behind the plate for as long as they can.

Anthony Castrovince is a reporter for MLB.com. Read his columns and his blog, CastroTurf, and follow him on Twitter at @Castrovince. This story was not subject to the approval of Major League Baseball or its clubs.