Twenty-two catchers have caught 1,000 games before their 30th birthday. The list begins with Johnny Bench (1,498) and ends with Lance Parrish (1,039). Joe Mauer, newly 26 years old, is not yet on the list, and is still waiting to make his season debut. In the meantime, he’s frozen at 498 games behind the plate. Should he average just over 100 games a season behind the plate between now and turning 30, he will join Bench, Parrish, and such luminaries as Pudge Rodriguez and Jason Kendall in this small, historical group. As the wildly divergent career paths of the players mentioned suggest, Mauer’s ultimate inclusion in the Mille Catchers group might mean something, and it might not. Consider this a cautionary tale.

The two most recent catchers on the “1,000 x 30” list are Ivan Rodriguez, who had caught 1,426 major league games by the time he reached the big 3-0, the fourth most of all time behind Hall of Famers Johnny Bench and Ray Schalk, eight-time All-Star Ted Simmons, and Kendall. Having reached the majors at the age of 19, Pudge logged 169 more games behind the plate than the fifth-place catcher on the list, Gary Carter. Carter made the majors at 20, but spent a couple of years hanging around the outfield corners while the Expos tried to make sure that they didn’t like Barry Foote better. Kendall is further down the list, tied with 1930s catcher Frankie Hayes for eighth place, but still only 52 games behind Carter.

As might have been expected of a former first-round draft pick (1992), Kendall was a terrific hitter, especially by the standards of his position. Not many catchers in major league history have been consistent high-average hitters over the course of a long career—a catcher’s hands are usually too abused for that kind of bat control. Just four backstops have hung up their shin guards with a .300 average in a career of 5,000 or more plate appearances: Mickey Cochrane (.320), Bill Dickey (.313), Mike Piazza (.313), and Ernie Lombardi (.306); if Rodriguez retired today, he would be the fifth at .301. At first, Kendall seemed like a good candidate to join them. He hit an even .300 his rookie year, and after enduring a .294 sophomore “slump,” he got his average into the .320s and kept it there for three straight seasons.

On July 4, 1999, Kendall suffered a grotesque injury when he tried to beat out a bunt hit and his foot caught on the first-base bag, snapping his ankle. He missed the rest of the year. When he came back, his speed had been compromised—he had been a good-percentage basestealer in his first four seasons, going 71-for-87 on the bases, but his days as an effective basepaths commando were gone (though he kept trying for a while). However, his bat was right where he had left it, as he hit .320/.412/.470. with a career-high 14 homers. His next two seasons were disappointments, as he slumped to a combined .274/.342/.357. However, he rebounded in 2003, hitting .325/.399/.416, and then followed up by hitting .319/.399/.390 in 2004. It should be noted that his power was ebbing—he hit just six home runs in 2003 and only three in 2004, but his ability to hit for average clearly remained.

When the 30-year-old Kendall was traded to Oakland that winter, his career rates stood at .306/.387/.418. He’s been no fun ever since. In his first year with the Athletics he batted .271/.345/.321 with no home runs. The next year his batting average rebounded to .295, but the complete lack of any power in his bat made the season a net loser. Overall, since turning 30, Kendall has hit .263/.336/.321, inclusive of his first 17 games this season. He will celebrate his 35th birthday on June 26.

Was Kendall’s fall the inevitable result of his heavy workload? The Pirates did ride him hard, particularly in this century. He started as many as 146 games behind the plate and got few true days off, appearing in 152 games in 2000, 157 in 2001, and 150 in 2003. There’s a classic logical fallacy known by snooty Latin-lovers everywhere as post hoc ergo propter hoc—after this, therefore because of this. It is clear that Kendall’s physical tools aren’t what they once were, and that years of squatting, blocking the plate, and handling the dreck pitching that the Pirates’ system pushed out could be to blame, but we can’t know for certain.

In comparison to Kendall, Ivan Rodriguez has been spectacularly durable. His career averages were .305/.342/.489 at the conclusion of his age-30 season. Rather than shutting down immediately, he had two strong seasons in the years immediately thereafter, batting .297/.369/.474 for the 2003 Marlins, and .334/.383/.510 for the 2004 Detroit Tigers. He began showing signs of age the next year, but having hit .284/.314/.419 in 401 games from 2006 to the present, Rodriguez has retained much more of his original skills than Kendall has, and that’s despite far more mileage on his chest protector. Clearly not all catchers respond to their workloads in the same way—or the problem isn’t workload at all, but something else, perhaps injury, normal aging, or a combination thereof.

Mauer is expected to be activated on Friday. At 6’5″ and 220 pounds, he’s not too much like the 6’0″, 180-pound Kendall. However, as we remarked in BP2K9 this year, they do have one thing in common: through his age-25 season—which is to say, last year—Mauer has hit .317/.399/.457. Through his age-25 season, Jason Kendall batted .312/.399/.451. Kendall had caught 490 games to that point; Mauer, coming up a year younger, has caught 498. The Twins have been more careful with their catcher’s workload than the Pirates ever were with Kendall’s, but even so, the games pile up, and both he and the club had best hope that the slide was peculiar to Kendall, and not something that comes unbidden with the job requirements of being a top young catcher.

A version of this story originally appeared on ESPN Insider Insider.