Anyone who has watched the Royals over the past two Octobers knows that catcher Salvador Perez has been a major piece of the team's success, as a steady presence behind the plate who also has come up big with the bat.
But due in part to his team's deep postseason runs, Perez also has worked incredibly hard. In fact, his workload behind the plate has been, in some ways, unprecedented. It's a fact that complicates the Royals' decision on Tuesday to give Perez a five-year, $52.5 million extension, when they already had him locked up through 2019, thanks to one of the most team-friendly contracts in baseball.
• Royals, Perez agree on extension
Kansas City obviously had its reasons for rewarding a player who was integral to the franchise's rebirth and 2015 championship run. But purely from an on-field standpoint, it's worth examining what Perez has endured physically and how that could impact him over the life of his new deal.
It's well known that Perez has spent an awful lot of time behind the plate, but the gap between him and the rest of the field is stunning. After catching 113 Major League games from 2011-12, Perez started 126 at the position in '13, 143 in '14 (plus 15 in the postseason) and 137 more last year (plus 16 in the postseason). Here are the top five catchers in total starts over that span, playoffs included:
1. Perez, 437
2.Yadier Molina, 393
3. Russell Martin, 353
4.Buster Posey, 351
5.Jonathan Lucroy, 344
Perez caught far more than anyone else during the regular season, and the fact that he played nearly every inning of two consecutive World Series runs only widened the chasm.
Innings are of course a more precise measure of workload than starts, and in Game 4 of last year's World Series against the Mets, Perez broke Randy Hundley's longstanding record for most frames caught (regular season and postseason) over a two-year span since 1914, according to STATS. With that in mind, here is a look at the hardest-working catchers going back a bit further, to 2013.

Over the past three seasons, Perez has spent the equivalent of about 46 more nine-inning games behind the plate than any other catcher. The innings gap of 1,189 2/3 between him and the 10th-place catcher, A.J. Pierzynski, is greater than the 2015 innings total of any catcher besides Perez.
In other words, Perez has logged more or less an entire extra season behind the plate over the past three years, when compared with most other regular backstops. That's mind-boggling, and while Perez is built like a tank -- he is listed at 6-foot-3, 240 pounds -- that also makes him a big target for foul tips and other hazards of the position. There's no question Perez has taken some serious abuse.
Of course, Perez also has the benefit of youth, as he won't turn 26 until May 10. But even in the context of his age, Perez's innings total stands out from the pack. In fact, it ranks second in history to Ted Simmons for a catcher from his age-23 season through his age-25 season, playoffs included.

That type of workload has to be concern for the Royals, especially considering how Perez's offensive numbers have been trending. While he has increased his home run total every year, his on-base percentage and OPS+ have continued to drop. In 2015, Perez set a career high in strikeout rate and a career low in walk rate while posting a .280 OBP and 89 OPS+, which ranked 12th of 16 catchers who logged 400-plus plate appearances.
At the same time, the above list also offers hope. Take Simmons, who not only had more innings at 23-25, but also put in more than 3,000 innings behind the dish prior to that period. He racked up more than 3 wins above replacement in seven of the following eight seasons, with an average of 3.8, not hitting a wall until he was 34.

To use two more recent examples, Martin and Brian McCann both have endured some injuries and other struggles at times, but from age 26-31 averaged 3.1 and 2.3 WAR per season, respectively, scoring large free-agent contracts along the way. The nine catchers besides Perez with the most total innings from age 23-25 averaged 12.7 WAR in those years, 12.6 in the next three and 11.2 in the three after that. So as a group, there was very little dropoff during the window covered by Perez's extension, even though several also caught a lot more in the big leagues before age 23 than Perez.
Every player is different, and it's impossible to predict what circumstances might arise over the next several years. But despite Perez's historic workload behind the plate, there is at least some reason to believe he can hold up well enough to make good on the Royals' investment.