Why 2024 will be the year of J.T. Realmuto's decline

Oct 24, 2023; Philadelphia, Pennsylvania, USA; Arizona Diamondbacks left fielder Corbin Carroll (7)
Oct 24, 2023; Philadelphia, Pennsylvania, USA; Arizona Diamondbacks left fielder Corbin Carroll (7) | Kyle Ross-USA TODAY Sports

This looks like the season when J.T. Realmuto’s skills decline, probably precipitously.

It’s not your fault, J.T.; it’s just Father Time.

Realmuto is entering his age 33 season in 2024, turning the dreaded age next month. Especially in recent seasons, that’s become a perilous point in time for career catchers, the stage of their career in which performance decline begins to set in.

If you look at the recent history of front-line catchers who were active at that position in both their age 32 and age 33 seasons, the decline pattern is obvious. Since 2000, there have been 16 catchers who were established front-line backstops at both age 32 and 33.

Those 16 averaged a 9% decline in offensive production between their age 32 and age 33 seasons. The defensive decline was even more dramatic, from +1.0 to -1.0 Defensive Runs Saved.

Only four of the 16 saw their OPS improve between the ages of 32 and 33. Of the 15 whose age 32 and 33 seasons fell during the Defensive Runs Saved Era – that is, since 2003 – all but three registered defensive declines.

Let’s start with offense. Here’s a look at the change in OPS figures for the 16 from their age 32 to age 33 seasons. The catchers are listed alphabetically.

Player                                   Age 32  Age 33  Change

Yasmani Grandal              .939        .570        -.369

Jason Kendall                     .709        .610        -.099

Mike Lieberthal                 .783        .755        -.028

Paul LoDuca                        .690        .714        +.024

Javy Lopez                        1.065     .872        -.193

Russell Martin                   .787        .733        -.054

Bengie Molina                   .731        .767        +.036

Yadier Molina                    .660        .787        +.127

Miguel Montero               .684        .656        -.028

Sal Perez                            .757        .714        -.043

Mike Piazza                       .957        .903        -.054

A.J. Pierzynski                 .755        .688        -.067

Jorge Posada                  .922        .881        -.041

Ivan Rodriguez                .893        .735        -.158

Jason Varitek                  .872        .856        -.016

The average decline in OPS for those 11 quality catchers was about 59 percentage points, from .810 in their age 32 seasons to .750 in their age 33 seasons.

In Realmuto’s case, the decline may have already begun to set in. He produced a .762 OPS in 2023, down from .820 one season earlier and off his career .785 average.

At the catching position, offensive decline with age is virtually a given. The real alarm bells go off when the defense begins to deteriorate. Yet that’s what happened with seven of the 10 catchers who competed at the position since the Defensive Runs Saved metric came into vogue. Piazza, whose age 32 season pre-dated DRS by one year, is excluded from this calculation.

Here’s the Defensive Runs Saved data.

Player                                   Age 32  Age 33  Change

Yasmani Grandal               -1            -5            -4

Jason Kendall                     11           20           +9

Mike Lieberthal                  -9          -14           -5

Paul LoDuca                        5               0            -5

Javy Lopez                         4              1             -3

Russell Martin                   8               3              -5

Bengie Molina                   4               3              -1

Yadier Molina                  10           1              -9

Miguel Montero               0             -3             -3           

Sal Perez                         -4            -11           -7

A.J. Pierzynski               -5           0           +5          

Jorge Posada                -2          -12          -10

Ivan Rodriguez              -7             6          +13

Jason Varitek                 0             -8             -8

Again, Realmuto is already trending downward. Following a 2022 season in which he generated a +11 DRS, his score fell to -4 in 2023, a 15-run dip in defensive efficiency.

The one thing Realmuto may have going for him this coming season is his relatively lighter workload behind the plate. To date, he has played in 1,047 games behind the plate. The average workload for the 16 catchers shown above – through their age 32 seasons – was 1,120 games, about a half-season more.

But if his decline this season mirrors the recent historical pattern, his .762 OPS of 2023 would fall to .702 in 2024. That would be measurably below the MLB average, which in 2023 was .734. The average for catchers who started at least half their teams’ games was .719.

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