A catcher's dilemma: How much longer can Buster Posey stay behind the plate?

Buster Posey has made two trips to the disabled list in his major league career, and they both left a mark.

In May 2011, Posey suffered a devastating injury to his left leg in a home plate collision with Miami Marlins outfielder Scott Cousins. Posey returned to make four All-Star teams, lead the San Francisco Giants to titles in 2012 and 2014, and avoid the DL until this month, when he took a 94 mph fastball from Arizona's Taijuan Walker off the helmet and spent a week recovering from a concussion.

Most days behind the plate, Posey is subject to the same predictable drumbeat of hazards. He's a magnet for foul tips off the mask or knuckles, not to mention the stray bat recoil off the noggin. And when he's not sprawled in the dirt taking an errant slider off the cup, his knees and back feel the strain from all those hours in a crouch. He has learned from experience that life on theSalvador Perezblack-and-blue plan can tax a man's pain threshold.

Nevertheless, Posey is resolute. When it's suggested that a move to a different position could be a boon to his career, he stands his ground.

"If I ever got to the point where they said, 'Hey, we feel like this is better for the team,' I'm not gonna be a guy that's stubborn and says no,'' Posey says. "Until they tell me that, my value is behind the plate. As cliché as it is, it's about winning ballgames.''

Giants general manager Bobby Evans confirms the team has no plans to move Posey anytime soon. The Giants signed veteran free agent Nick Hundley with the expectation that Posey would start 115-120 games behind the plate. Throw in 15-20 appearances spelling Brandon Belt at first base and a few at DH during interleague play, and Posey is looking at a regimen of 145 games or so this season.

"When you have a guy that's led us to three titles, a lot of it is because of his preparation and guidance of the starting rotation and the bullpen,'' Evans said. "I think it distinguishes him from other positions -- and other guys. My mindset is we're a better team with Buster back there, and as long as we can keep him back there, we want to do it.''

It's hard to envision Posey maintaining his current schedule for the long haul, though. His nine-year, $167 million contract runs through 2021, and if the Giants were to exercise his $22 million club option for 2022, Posey would be 35 at the end of the deal. Fellow catcher A.J. Pierzynski started 104 games for the Atlanta Braves at age 38, and the Cardinals' Yadier Molina just agreed to a three-year contract extension at age 34, but they're notable exceptions to the rule.

Most front-line catchers have to deal with an alternate reality: Beyond the daily grind, the passage of time is the biggest threat to their claim to the position.

As the Giants assess the fallout from ace Madison Bumgarner's dirt bike injury and a start so poor it has put the entire season in jeopardy, Posey's role with the organization grows ever more complex because of some shifting circumstances.

Defensively, he's at the top of his game. Posey ended an eight-year run by Molina with a first career Gold Glove in 2016, and the metrics reflect his all-around excellence.

At the same time, Posey's power numbers have slipped. Since 2014, his home run totals have dropped from 22 to 19 to 14, with a corresponding decline in slugging percentage from .490 to .470 to .434. Although it's hard to draw any conclusions from this season because of the small sample size and Posey's early DL visit, he has only one home run and three RBIs in 61 plate appearances.

Industry standards for the catching position indicate that a reversal is unlikely as Posey, 30, continues to age. According to John Fisher of ESPN Stats & Information, 104 catchers have posted an OPS above .800 over the past 10 seasons. Of that group, just 16 (or 15 percent) were 32 or older.

That ratio assumes greater meaning when contrasted with the positions where catchers eventually gravitate. Of the 203 third basemen who have surpassed an .800 OPS over the past 10 years, 27 percent were 32 or older. The rate increases to 28 percent for the 165 left fielders, and 29 percent of the 215 third basemen.

Beyond that, the value of a given set of numbers varies from one position to the next: A catcher with an .800 OPS is 14 percent better than the average catcher, but a left fielder with an .800 OPS is only 8 percent better than the average left fielder.

So when front offices consider moving catchers to another spot, two questions predominate: (1) Will a position change help a catcher stay healthy and enhance his career longevity; and (2) if a catcher is a strong producer behind the plate but middle-of-the-pack at another spot, what's the point?

Like Posey, Texas Rangers catcher Jonathan Lucroy is 30 years old with roughly 700 career starts behind the plate and a concussion on his résumé (sustained on a foul tip off the mask in September 2015). Unlike Posey, Lucroy is eligible for free agency in November. He knows his value on the open market is higher because he produces at a position where offense is tough to find.

"I'm a catcher first,'' Lucroy said. "It's my best position, and I take a lot of pride in that. I've said this in the past when the question was brought up: I would go from an above-average catcher to a below-average first baseman. It would be one thing if I'm hitting 30 home runs a year, but I'm not.''

Through the years, some accomplished catchers have made the switch for a variety of reasons. In 1992, the Astros moved Craig Biggio to second base because he weighed 165 pounds and they feared he might not survive a violent home plate collision. Biggio, then 26, went on to amass 3,000 hits and make the Hall of Fame. Joe Torre also experienced a career revival after the St. Louis Cardinals shifted him from catcher to first base at age 28. Two years later, he won a batting title (.363) and a National League MVP award.

In 2014, the Minnesota Twins put Joe Mauer at first base because of ongoing health concerns. Mauer was dealing with the fallout from a concussion -- not to mention knee, back, hip, shoulder and leg issues -- and it was the best option available for the Twins to maximize the five years left on his $184 million contract extension.

"Most catchers would want to play the position as long as they can,'' Mauer said. "I really enjoyed the position and I miss it. But obviously, mine was more of a necessity. I tried to find as many doctors as I could to tell me it was OK, but I didn't find that.''

While Mauer has done a better job staying on the field at first base, his numbers don't stack up very well at his new position. In 2016, Mauer's .389 slugging percentage ranked 22nd among MLB first basemen with at least 400 plate appearances.

For Posey and other catchers who eventually contemplate a move, the emotional repercussions are hard to ignore. Of the eight non-pitcher positions on the field, catchers and shortstops are the most territorial when it comes to surrendering their terrain.

Johnny Bench reflected the overall sentiment in a 1981 New York Times interview, and it still holds true for the fraternity. While lamenting his sore elbow, cracked toenails and persistent back spasms, Bench described the constant lure of the catching position.

"There's nothing like it,'' Bench said. ''You have a sense of control. Your time is always full. And when it's going good, when you're in rhythm with the pitcher, you feel like a symphony conductor. You can be 0-for-4 at the plate, but if you call a good game, or throw a runner out stealing, or block a run from scoring, you feel you've contributed.''

In 1982, Bench moved from catcher to third base in hopes of adding a final flourish to a Hall of Fame career. He made 19 errors in 103 starts at third and retired the following year at age 35.

Lucroy, a two-time All-Star, took up catching as a 12-year-old in Little League and warmed to it immediately. In the 18 years since, he's found that the adrenaline rush and sense of gratification he gets from the position outweigh his self-preservation instincts.

"All of us catchers, when we're together, we understand the hardships of the position,'' Lucroy says. "A lot of other guys are like, 'Tough it out.' But they don't realize what it feels like to get a foul tip off the throat. You've got to be stupid or crazy to catch. There's no way a sane person would get back there and get beat up like that all the time.

"I take the field every day knowing I'll probably have arthritis the rest of my life, and things will pop up when I'm 60 that stem from this. But you know what? That's OK. I'm willing to make that sacrifice right now, because I love what I do.''

Posey feels the same sense of achievement when he pores over the scouting reports and helps nurture pitchers through a low-scoring victory. In an effort to prolong the experience, he's constantly thinking of ways to keep himself fresh and fend off the ravages of age. Maybe it means spending a little less time in the batting cage, or more time in the trainer's room.

"I can look at age curves and try to learn from that and say, 'All right, maybe I need to adjust some workouts or spend more time in the cold tub,'" Posey said. "There are different things I might have to do more now than when I was 23, 24 or 25.''

As his ninth MLB season ratchets up, Posey's emotional investment makes it hard for him to imagine watching the game unfold from anywhere but behind the bars of a mask.

"I'm not saying this in an egotistical way, but I think there's value in having a good hitter behind the plate and being able to put a bat at first base as well,'' he said. "Maybe my career is three years shorter this way. But I know I'm getting the most out of it.''