Though his arm is pitiful, Travis D’Arnaud need not be a game-breaking hitter to merit a starting job with the Mets.

Only two seasons ago, baseball glimpsed what could be Travis d’Arnaud’s ceiling. In 2015, he posted the third-highest isolated slugging percentage (ISO) and third-best weighted Runs Created Plus (wRC+) among catchers with 250 plate appearances or greater. Two years ago, he was one of many bright spots on an up-and-coming, pennant-winning New York Mets team.

D’Arnaud’s 2016 season, however, was a disaster. He spent eight weeks on the disabled list with an injury to his rotator cuff. He hit so poorly (74 wRC+ and a slash line of .247/.307/.343) that he finished the season in a timeshare with Rene Rivera, a career .213 hitter. D’Arnaud’s line drive rate plummeted (21.4% to 16.9%), he stopped driving the ball in the air (41.7 FB% to 30.8%). Naturally, his groundball rate spiked drastically (37.0% to 52.2%) – a recipe for disaster for any slow-footed catcher.

As bad as his bat was, that is not the reason why people are buzzing about Travis d’Arnaud this spring. In the small 52 PA-sample that was Spring Training, d’Arnaud had a .956 OPS. On the other side of the ball, however, his arm has been nothing more than abysmal. Runners stole 12 bases with d’Arnaud behind the dish, and the only caught stealing was on a pitcher pickoff. Things came to a head when the Houston Astros ran all over d’Arnaud on March 24th, stealing four bases in four attempts including an embarrassing Jake Marisnick stolen base on a pitch-out.

Controlling the running game is not a new problem for the Mets backstop. In 2014, d’Arnaud’s longest and healthiest Big League season, he caught only 19% of attempted base-stealers (league average was 28%). Last season, he caught 22% of runners (average was 27%), but by this time the secret was out regarding his weak arm. Runners attempted to steal 78 times during d’Arnaud’s 615.2 innings behind the dish. Put differently, for every nine innings d’Arnaud plays as a catcher, he can expect to see 1.14 stolen base attempts. That isn’t as bad as Mike Piazza’s career rate of 1.21 SBA per nine innings, but it’s uncomfortably similar to the patron saint of bad-arm catchers.

The prevailing sentiment from sportswriters and management is that d’Arnaud’s bat will be enough of a reason to keep him in the lineup. Frustratingly, these blithe statements fail to go into the analytical detail we crave. The real question is: How well does Travis d’Arnaud need to hit to cancel out his terrible arm?

The first hurdle we need to clear is to estimate d’Arnaud’s playing time. Last season, starting catchers averaged just under 120 games played and about 1,017 innings behind the dish. If we assume d’Arnaud can stay healthy and will be among qualifying catchers, let’s make the math easier and estimate 1,000 innings caught.

Now, let’s extend his opponents’ 2016 stolen base attempts over these 1,000 innings. 78 SBA in 615.2 innings averages out to about 127 attempts in 1,000 innings. With his 22% CS rate, his numbers equate to 99 stolen bases allowed to 28 runners caught. This ratio is not quite Piazza-bad (he allowed 155 stolen bases and caught only 34 in 1996!), but still pretty terrible. For modern context, Derek Norris led the league last year with 76 stolen bases against. D’Arnaud would blow him out of the water.

*Mark J. Rebilas-USA TODAY Sports*

How costly are each of these stolen bases? One way to determine this would be to extend d’Arnaud’s stolen base runs saved (rSB) from 2016 over 1,000 innings. Since this is a little bit of an obscure statistic, you can find the methodology behind the metric on the Fielding Bible here. FanGraphs has d’Arnaud at minus four over his 615.2 innings. Scale that, and d’Arnaud’s arm would cost his team about 6.5 runs in 2017.

The good news is that measuring offensive value in runs is pretty simple arithmetic. The corollary offensive statistic here is weighted runs above average (wRAA). Following our estimation of 1,000 innings behind the dish and about 120 games, we will keep the trend of easy numbers and assign d’Arnaud 450 plate appearances.

Here is the formula:

wRAA = ((wOBA – league wOBA) / wOBA scale) x PA

And with variables filled in:

6.5 = ((wOBA - .318) / 1.212) x 450

Which leaves us with a wOBA of .336 over 450 PA in order for the value of Travis d’Arnaud’s bat above the average to break even with value lost due to his arm. That is roughly equivalent to Ian Desmond’s numbers from last season, who slashed .285/.335/.446 and finished 87th among 175 hitters with 450 PA or greater. Such a wOBA is achievable for d’Arnaud, who reached as high as .355 in 2015.

That being said, catcher defense is far more than controlling the running game. One of the biggest and trendiest aspects of catching is framing, which for so long was undervalued but is now a mainstay when defining what makes a good defensive catcher. By both StatCorner and Baseball Prospectus, Travis d’Arnaud rates as an above-average framing catcher. Scaling his framing runs to 1,000 innings, d’Arnaud’s left arm would save his team 11.7 runs according to Baseball Prospectus, which nearly doubles the absolute value of runs lost by his right arm on stolen bases. Under the same sort of calculations, d’Arnaud would also save about 1.6 runs by blocking pitches in the dirt.

If we take all of our measurable catcher data into account, Travis d’Arnaud is actually a decent defensively catcher. His hitting need not solely make up for his bad arm, since his framing skills more than neutralizes it. Even with the gradual depreciation of framing value as it becomes more standard, d’Arnaud does not need to be a freak at the plate either. A solid season at the dish will make up for whatever damage he does behind it.

All of these statistics are context-independent. For the most part, stolen bases are not. That is to say, a stolen base becomes more valuable in closer games and in later innings. Therefore, although d’Arnaud will not need to hit like Yoenis Cespedes to account for his weak throwing arm, the Mets should still consider a defensive replacement in tight games. Travis d’Arnaud will not sink the Mets because he cannot throw out runners. However, his positives — his framing ability and offensive potential — will go a long way in righting the ship.

Edited by Joe Sparacio, Emily Greitzer.

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