For as much as we focus on catcher defense these days, the battery dynamic remains beyond our grasp. We know pitchers and catchers work together to form a gameplan and negotiate pitch type and location, but the heavy lifting is often left in the dark. What illumination we do receive often shines from second-hand knowledge, or analysis that is prone to fundamental attribution errors. As a result, analyzing gamecalling and the like is a tough, if not impossible, pursuit from outside a team's walls.

Yet sometimes we do get a glimpse of the inner-workings of a relationship. Take Sam Miller's piece from last September on the Jeff Mathis-Jose Fernandez battery. Miller examined just how Mathis had impacted Fernandez's game, and found some evidence that the oft-derided backstop helped the oft-admired hurler more than we might have thought. The case? An increased usage in curveballs.


The 2014 season is less than a week old, but we might have another example of a veteran catcher helping a younger pitcher with a change in approach—and, just like with Mathis and Fernandez, this one comes from Miami.

When the Marlins signed Jarrod Saltalamacchia over the winter, the presumption was he would outhit last season's Rob Brantly-Mathis combination in order to earn his keep. Saltalamacchia should do just that, yet the biggest impression he's made thus far might not have come on a baseball, but on Nathan Eovaldi. (Before we get to the good stuff, here's where we drop the obligatory caveat. Drawing too wide a conclusion based on one start is madness. This is merely highlighting an interesting approach.)


If big velocity is intoxicating, then Eovaldi has always gotten the whole town drunk on his throw nights. Last season the erstwhile Dodger averaged 96 mph on his fastball, and on Tuesday night he sat in the 97-98 mph range during the game's first two innings. Eovaldi showed decent command, working the corners and missing off the plate when his pitches strayed from the target. Combine the velocity and location and it's fair to call Eovaldi's heater a well-above-average offering, even if it doesn't feature outstanding movement.

That big-time raw arm strength took a backseat on Tuesday to another development in Eovaldi's game: how he approached left-handed hitters. Taming opposite-handed batters has been an issue for the right-hander, who entered the season with a 100-point OPS split between his work versus righties (.671) and lefties (.771). The biggest reason for his struggles is that he lacks a reliable changeup, and the expectation tends to be that he'll continue to scuffle until he learns how to throw a workable change-of-pace.

But on Tuesday Eovaldi showed some creativity with how he deployed his slider, the best secondary pitch in his arsenal, and the only non-fastball offering he used with regularity. In fact, it was the highest rate of sliders he's used against lefties since September of 2012. The most notable slider on the night came at the end of the first inning, when he back-footed one against Carlos Gonzalez that looked like this:


The potential ramifications here are obvious. If Eovaldi can consistently back-door and back-foot his slider against left-handed batters, then he should become more effective versus them, and thereby minimize the need for a qualify changeup. He wouldn't be the first right-handed pitcher to succeed this way. In recent years, the league has seen Justin Masterson, Ervin Santana, Edwin Jackson, and Chris Archer, among others, carve out worthwhile careers without boasting high-quality changeups.

The most interesting comparison to make here is John Lackey, but not for the reasons one might expect. Lackey didn't start using his slider against left-handed hitters nearly as often as he does now until he joined the Red Sox in 2010. Victor Martinez caught Lackey most starts in that season, but it was Saltalamacchia who served as Lackey's primary catcher in his other full seasons in Boston. In both those seasons, Lackey saw his slider percentage against lefties increase:

The connection from Lackey to Eovaldi then is really the Saltalamacchia factor. There's no telling who planted the idea in Lackey's head to use his slider against lefties. Perhaps he arrived at the conclusion on his own, or got it from Martinez, or some Red Sox coach or player. Odds are, Saltalamacchia wasn't the root of the idea. What's interesting though is that he seemingly embraced the technique; maybe not just with Lackey for those two seasons, but now on his new team with Eovaldi.

Obviously it's too early to say for sure, and there are other possible explanations here. Saltalamacchia could not have been involved in either decision. Eovaldi might have received the advice from a Marlins coach, or simply felt his other secondary offerings were unsuitable for usage before taking the mound on Tuesday night. This is just something to keep in mind as the youngster takes his second turn in the rotation come Sunday, and continues to try to shore up one of the weaknesses in his game.


Miller was talking about himself when he wrote "I can’t make my brain stop thinking the way I trained it to," but he could have been voicing the inner dialogue of any pitcher who receives new instruction from his backstop. The successful staff handlers are those who can coerce pitchers into trying something new. Saltalamacchia just might be one of those backstops.