The Miami Marlins started off the season with incumbent Jarrod Saltalamacchia playing the primary catcher role and Jeff Mathis playing backup to him. Saltalamacchia was the $21 million signing in which the Fish smartly invested before the 2014 season, but his disappointing 2014 campaign started him off on poor terms with the team. But a slow start at the plate (.069/.182/.207, .184 wOBA in 33 plate appearances) prompted the Marlins to pull the trigger and release Saltalamacchia.
At the time, I thought the move was premature (more on that later) given the fact that the Marlins were dealing with a Mathis injury at the time, but the move was done regardless and the Fish would have to manager the consequences. They did so by starting prospect J.T. Realmuto as their full-time catcher starting in April. The team let Realmuto take over for 126 games (467 plate appearances), and while he never lit the world on fire on either side of the field, he did well enough to be an above-average contributor for the Marlins.
Right off the bat, you can see that catchers have to do very little at the plate to be successful overall provided they play average or so defense. Realmuto did not perform up to the standard he set in Double-A last year, but he never had to in order to be a good big leaguer. The appeal for Realmuto was always that he was a better defender than Saltalamacchia, and the bat just needed to be close enough.
"Close enough" it was. Realmuto flashed some reasonable power for a guy who only once hit more than ten homers in a minor league stop, as he smacked ten bombs this season and put up a .147 ISO, the second-highest of his career at any professional level. A big part of that ISO was the seven triples he hit, however, and those are far more likely to be a product of his speed rather than his power bat. Speed is something we are not used to seeing in catchers, but Realmuto does have it, as most sources put him at about one run above average in the baserunning department. For a 24 year-old rookie catcher, these initial numbers did not seem unreasonable.
Still, there had to be some complaints. After posting a career-best 9.7 percent walk rate in his breakout Double-A campaign last year, he disappointed with mediocre plate discipline numbers. Realmuto was aggressive at the dish, swinging at 50 percent of the pitches he saw, the third-highest rate of any Marlin with more than 200 plate appearances. This meant that he swung a lot at good pitches as well as bad ones; his 33 percent out-of-zone swing rate was tied for fourth on the team. The approach led to a minuscule 4.1 percent walk rate this year, which contributed to his sub-.300 on-base percentage. Among the 211 Major Leaguers with at least 400 plate appearances in 2015, Realmuto's .290 OBP was the 21st-lowest in baseball, ahead of only one other Marlins (Ichiro Suzuki).
However, the plate discipline was not all bad news. Only two Marlins made better contact than Realmuto's 86 percent rate, as he was able to prevent strikeouts to the tune of a meager 15.0 percent strikeout rate. This was in line with his minor league reputation as a solid contact hitter. Unlike the other two high-contact guys on the roster, Ichiro and Dee Gordon, Realmuto's pop provides him some nice added value to his contact. He is not some slap hitter who will never hit the gaps; Realmuto hit 28 doubles and triples this year, though he only put up a .306 wOBA on fly balls this season.
The Fish were happy with all of the batting, good or bad, as long as the defense was fine, and that turned out to be the case. Realmuto was about league average at catching baserunners and met the same marks for blocking pitches at the plate. This was a far cry from Saltalamacchia, who was one of the worst defenders in terms of base stealing in 2014. Realmuto's defensive season was only blemished by his supposedly poor pitch framing. According to Baseball Prospectus, the young catcher cost the Marlins about 39 strikes compared to an average pitch-framer, yielding about six runs below average.
Overall, Realmuto's exploits have to be considered a success. While he was only 12th among 16 big league catchers with at least 400 plate appearances, his offensive performance was ranked 10th overall thanks to his positive baserunning. The defense should improve over time and get Realmuto to the next level of play. It is too early to call him a cornerstone piece on this roster, but the Marlins desperately needed some young, cost-controlled position talent, and they probably found one in Realmuto.