When the Rays traded for Rene Rivera during the offseason, it was a typical Rays acquisition. Rivera was coming off his first season as a full-time catcher, but he showed promise with the bat and was one of the best defensive catchers in the league. He was set to step in as Jose Molina's replacement and featured a similar skill set.
But the 2015 season has been a far cry in comparison to 2014. His wRC+ has plummeted from 114 in 2014 down to 44, and he has posted a .217 on base percentage so far. Some of this collapse looks to be BABIP-driven, as his BABIP fell from .301 in 2014 to .224 in 2015. But, if we look at his underlying statistics, it looks like this has not been just a bout of bad luck, and instead a change in performance as well.
Rivera's hard-hit ball rate has been decreasing over the past few seasons. In a small sample in 2013, his hard-hit rate was elite at 39.6%, but has since fallen to below league average, as shown by the image below.
Work from Jeff Zimmerman has shown that hard hit rate is significant in determining BABIP, so the weaker contact supports Rivera's low BABIP.
Additionally, Rivera has been hitting fewer line drives this season, falling from 21% in 2014 down to 18.1% in 2015. Line drives have the highest BABIP of all batted ball types at .676, so hitting fewer helps explain the lower overall BABIP. But, line drive rate has a very low year-to-year correlation, meaning that a player's LD% can have a lot of variability between seasons. This suggests that Rivera's LD% should start trending toward league average (20.9%).
Rivera is also hitting more infield flies this season, as his pop-up rate has increased from 3.20% to 7.16%. Pop-ups have a BABIP of essentially .000 because they are almost always caught. More infield flies would decrease Rivera's BABIP, so this change in batted ball profile supports his low BABIP this season.
Based on Rivera's performance this season, Bradley Woodrum's xBABIP formula suggests that his BABIP should be closer to .259, and Alex Chamberlain's new formula pegs Rivera at a .255 BABIP. Both suggest that Rivera should regress upward as the season progresses, but not close to his 2014 numbers. While last season was most likely a career year for Rivera at the plate, the Rays probably knew that already, and weren't expecting elite offensive production. What Rivera has excelled at, however, is defense. While talking to Sports Talk Florida before the season started, he said, "Last year I had a pretty good year as a hitter . . . but I really don't want to think about it, I just want to help my pitching staff first." Clearly, defense and calling the game is a much larger priority for Rivera.
Catcher defense is a developing area of baseball analytics. Because catchers influence many parts of the game, and results are often interdependent on other players (like pitchers), identifying true catcher defensive skill can be difficult. However, Baseball Prospectus released their own catcher defense metrics, and quantified not only framing, but blocking potential wild pitches and passed balls as well.
According to this measure, Rivera was the second best pitch framer in baseball last year, adding 25.2 runs from his framing ability. Even though he didn't add any runs blocking pitches, he still added about 2.5 wins to the Padres last season (10 runs = 1 win). However, Rivera's framing statistics haven't been as spectacular with Tampa Bay as they were in San Diego. So far, he has added only three runs from framing and has slightly hurt the team in pitch blocking (-0.4 runs).
This is a complete deviation from his career trends. He has historically been a great defensive catcher in small samples, so seeing a poor performance like this is surprising. Pitch framing ages well, so we can't blame this on Rivera getting older. I believe that his worse framing metrics come from not only working with a new staff, but one that is young and has been fluid as well. As the rotation settles, I would expect Rivera's framing metrics to improve, and be closer to his previous performance.
Rivera's true talent level is, unsurprisingly, somewhere between his production from last season and this season. He should move from "bad" to "competent" at the plate, and his defensive stats should improve. But will this be good enough?
Catchers have a lot of defensive responsibility - they have a required skillset of blocking, framing, and throwing out runners that is unlike any other position in the field, and they are often tasked with calling the game. Because of this demand for defense, catchers tend to be weaker hitters. They usually have one of the lowest average wRC+ out of all positions in the infield, behind shortstop, and in some seasons, second base.
But a team that can get significant offensive production out of their catcher has a significant advantage. Instead of conceding offense for decent defense behind the plate, they can get both, which makes these players extremely valuable. This, combined with the financial aspect, helps explain why Buster Posey, Salvador Perez and Jonathan Lucroy land on Dave Cameron's list of players with the highest trade value.
While I think that the Rays might be a playoff team, they have holes in their roster, so a rebound for Rivera in the second half won't be the deciding factor in whether they play in October. But Rivera isn't a free agent until 2018, and the Rays need every advantage they can get when fighting against larger market teams in the division. If Rivera can start to turn things around to become a dual-threat again, he can be a difference maker for the Rays during the rest of this season and going forward.
Statistics used are from FanGraphs.