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Backup Catcher Candidates : Part One

A look at internal candidates.

Ronaldo Hernandez
Ronaldo Hernandez
Photo by Erica Denhoff/Icon Sportswire via Getty Images


To my surprise, this article grew unexpectedly large. Rather than skimp on the last portions, the article is split into two parts.

Part 1:

  • Returning backup catchers from last season: Jose Herrera.
  • AAA catchers for the Diamondbacks: Ronaldo Hernandez, and Adrian De Castillo.
  • AA/A+ catchers for the Diamondbacks: JJ D”Orazio, Christian Cerda, David Martin, and Caleb Roberts.

Part 2:

  • Free Agent Backup Catchers with power batting: perhaps Gary Sanchez.
  • Trade Candidates: perhaps David Fry (Guardians) and Cesar Salazar (Astros).

Table Comparisons.

The following tables compare the internal candidates for backup catcher. The first table compares batting. The second table compares defense as catcher. After looking at that tables, we will look at each candidate.

Data from Baseball Reference, Baseball Savant,, and FanGraphs.
Data from Baseball Reference, Baseball Savant,, and FanGraphs.

Considering the Candidates.

Jose Herrera. He is the lone remaining backup catcher from last season. Although his defense is average (with a slightly above average arm), his very-much-below-average offense (OBP of .296, SLG of .257, OPS+ of 54) hurts the team when he plays as backup catcher.

He has one option remaining, so if the Diamondbacks choose a better-batting backup catcher, Herrera could be retained as an emergency call-up catcher.

My view is that the Diamondbacks need to upgrade backup catcher with higher SLG and homers per PA. As we look at the candidates, Jose Herrera he will be the status-quo baseline.

Ronaldo Hernandez. He became a minor-league free agent when the Red Sox left him off their 40-man roster and then released him on 2 December. On 20 December, the Diamondbacks signed him to a minor-league contract.

Although he does not yet have experience in the Majors. Two things immediately impressed me.

  • Pre-2019, he was a top-100 prospect in baseball.
  • Comparing AAA performance of Herrera and Hernandez, Hernandez had the better SLG and Homers-per-PA.

There are concerns about his batting. Let’s look at three scouting reports about his batting:

2020. “Big and strong, he makes hard contact with strength-driven bat speed and shows feel for finding the barrel thanks to good hand-eye coordination. That Hernandez’s power plays almost entirely to his pull side during games speaks to his aggressive approach and leads some scouts to question his overall hitting ability. While he doesn’t strike out much, Hernandez does chase contact too often and will need to adopt a more selective approach as he works his way through the Minors.” — scouting report, 2020.

March 2021. “Furthermore, he doesn’t strike out much but his pitch selection leaves a lot to be desired. Hernández swings at some bad pitches, and while his hand-eye is good enough that he makes contact on many of them, they are not the kind of pitches against which he can tap into his above-average power potential. This is the biggest key for him to get the most out of his offensive ability. If he can let a few more fringe pitches go by and really impact the fat pitches, his bat will play more than enough for a major-league catching role.” — Matt Collins, SB Nation, March 2021

2022. “At Triple-A Worcester in 2022, he offered at a reckless 58% of pitches and posted a 41% chase rate (the big league average is about 33%).” — Eric Longenhagen, FanGraphs, June 2023

My view in December 2023. Ronaldo Hernandez addressed his batting issues in 2023, with continued progress likely. My reasons follow:

  • Looking at the trend of BB% and K% shows great improvement (see following table) Because of his large increase in BB% and large decrease in K%, my view is that he is making progress in selecting which pitches to swing at.
  • Most successful batters have unique quirks that are part of their approach and results. My view is that a high rate of infield pop-ups is his quirk. His increase in walks and decrease in strikeouts, while maintaining a high SLG, are much more valuable than eliminating infield pop-ups.
  • Another point is that it’s possible that infield pop-ups are a pitching skill. Perhaps pitching 4-seam fastballs and sliders on the inside part of the strike zone results in more infield pop-ups. Needless to say, Ronaldo Hernandez could learn to swing at less of those types of pitches.
Data from FanGraphs.

“The entire gap from bottom 10% to top 10% [of MLB pitchers] is 2.4%, or about five popups a year. Are those five popups worth something? Of course! They pale, though, in comparison to the value of getting more strikeouts or walking fewer batters.” — Ben Clemens June 2019

Ground Ball Rate. An additional concern is an increase in percentage of ground balls per the following quote.

“His batted ball data shows a sizable increase in ground ball rate over the last two years coupled with an extremely high popup rate that’s persisted throughout his career.” — Jack Sommers, SI Inside the Diamondbacks, December 2023

My view on ground ball rate. Two points follow:

  • While his ground ball rate in AAA increased from what it was at the lower levels of the minors (from 36.5-39.3% in 2018-2021 to 44.4-44.6% in 2022-2023), at the same time his pull percentage fell (from 53.2-55.6% in 2018-2021 to 45.0-46.9% in 2022-2023). Changing to an all-fields batting approach was an important step to reach the Majors.
  • More important is his ratio of Ground-Outs-to-Air-Outs (GO/AO). For Ronaldo Hernandez, his GO/AO fell from 1.15 in 2022 to 1.06 in 2023. In addition, in 2023 AAA, his 1.06 GO/AO (393 PAs) was much better than Jose Herrera’s 3.00 GO/AO (119 PAs).

There are concerns about his defense. His biggest defensive strength is his arm. It was rated as beyond amazing. Scouts have rated it 60 (FanGraphs’ Throwing) and 70 ( Arm Strength). Nevertheless, some writers have expressed concern about his pitch blocking and his pitch framing. Let’s look at a 2020 scouting report.

2020. “He’s improved as a receiver but still has a way to go to become average, and the same goes for his blocking skills. Improving his body and conditioning should help with the latter. If it all clicks, he could develop into an average defensive catcher who hits for enough power to compensate for his lack of average and receiving issues.” — scouting report

My view on his blocking. The defense table shows that Ronaldo Hernandez is the only backup catcher who is at the same skill level as Herrera (albeit it appears that Herrera may be slightly better). Herandez’s improvement may be due to changing his style of catching.

2023. “He improved over the last couple of years going to one knee style catching.” — Jack Sommers, SI Inside the Diamondbacks, Dec 2023

And blocking is a needed skill to reach the Majors.

“The minimization of passed balls may not say much about a catcher’s framing skill or his ability to handle a pitching staff, but it does seem that they have to be quite infrequent for a catcher to be deemed worthy of sticking behind the plate in a major league uniform.” — Nathaniel Stoltz, Jan 2014

My view on framing. This FG Article led me to believe that the one-knee catching stance (which Ronaldo Hernandez moved to a couple seasons ago) helps with pitch framing.

Because I did not find pitch framing data at the AAA level, his level of pitch framing performance is hard to quantify. However, it’s possible his framing is as good as Jose Herrera, who earned negative 4 framing runs, which ranked 51 out of 63 catchers with at least 975 pitches caught. Herrera ranked 62 out of 63 qualified catchers in another measure of framing, strikes in shadow zone.

Adrian Del Castillo. He has leadership strengths.

Playing in AAA at 24.3 years old, he is younger than the average AAA position player (26.6 years old). Although he is a bat-first catcher, his stats (especially SLG) show that he needs to improve his batting to reach the Majors. Because he is younger than average, he has time to make the needed improvement.

“There’s plenty to like about Del Castillo’s offensive profile, starting with his outstanding left-handed swing.” —

He is above average in throwing out runners attempting to steal a base.

His arm strength has improved and he tends to be accurate. —

My view is that he will be ready for promotion to the Majors within two years.

JJ D’Orazio.

His batting (OBP and SLG) looked great at the A+ level. His .027 homers per PA was a breakthrough career high.

When he was promoted to AA, his batting slumped in his first 145 PAs at the AA level. I’m optimistic that he will make needed adjustments in AA.

His caught stealing is above average.

“The Venezuela native moves well behind the plate and has long drawn praise for his ability to work with a pitching staff.” —

Christian Cerda.

Perhaps because of his bat’s raw power (.036 home runs per PA at the A+ level), Christian Cerda has a super-power: he walks a lot. His BB% was 22.6% at the A+ level.

He is one year younger than any of the candidates in the tables. Although his statistics have not yet risen above the candidates who have not yet reached the Majors, he may be the best bet to reach the Majors because the Diamondbacks like his makeup at catcher.

His story started when the Diamondbacks noticed him at age 16-17. They persevered until they found an opportunity to acquire him. In July of 2022, the Diamondbacks traded away David Peralta to acquire Christian Cerda.

“They [The Diamondbacks] went after him when he was an international amateur at 16-17, despite being born in the Bronx. That’s where a lot of these evaluations do start. Things change from the time [from when] they are 16-17 years old to when they are older in somebody’s else’s system. Their international scouts and cross checkers kept going back and looking in on his growth. They like his makeup, which is key to catcher. He’s bilingual, he’s got power, can control the strike zone. ‘Catching takes more projection at that age and development’.” — Jack Sommers, July 2022

David Martin. He is new to the minors. In 2022, he played for California Baptist College. He was named All-WAC first team at catcher and named as a top-30 catcher in Division 1 baseball.

In 2023, his OBP was good at the A and A+ levels, but his SLG was below average compared to other candidates for backup catcher. In his 13 PA cup-of-coffee at AAA, his OBP and SLG slumped, which is logical because he went directly from A+ to AAA. Advancing from rookie league to AAA in a year and a half is very fast! Likely, the Diamondbacks quickly saw his ability to play at a higher level.

Caleb Roberts. He is a utility player who plays catcher, first base, and outfield. His defense at catcher is below average, but as good as the other Diamondbacks catchers except for Moreno, Herrera, and Hernandez. My view is that he will compete with utility player Jace Peterson for a seat on the bench. Comparison points follow:

  • In addition to playing outfield, Caleb Roberts plays in two positions that are more likely to need his playing time (first base and catcher) compared to Jace Peterson, who (in addition to outfield) plays two lesser-need positions (second base and third base) due to the acquisition of Eugenio Suarez.
  • With the caveat that Caleb Roberts played in AA instead of MLB, in 2023 his batting was better than Jace Peterson (.382 vs .304 .OBP, and .523 vs .308 SLG).
  • Both Roberts and Peterson bat better against right-handed pitchers. Because most of their PAs were against right-handed pitchers, those split numbers were about the same as season numbers.

In the second half of 2023, Caleb Roberts’ batting significantly improved. In June/July/August, his OBP was .416 and SLG was .573)

Although his league and park adjusted Weighted-On-Base-Average (wOBA) is 35% above average in AA (wRC+ of 135), Caleb Roberts’ batting strength is best shown with his .573 SLG in the second half of 2023.


Four Points follow:

  • Jose Herrera is the only backup catcher returning from last season. His defense at catcher is average and his hitting is very much below average. If an upgrade was possible, he could be optioned to AAA as an emergency call-up catcher.
  • This spring, Jose Herrera and Ronaldo Hernandez will compete for the backup catcher position. Although there are concerns about Hernandez’s defense and batting, my view is that last season he addressed most (perhaps all) of these concerns. Spring training should see an interesting competition.
  • At some point in the next season, there could be a competition between Caleb Roberts and Jace Peterson for the utlity player bench spot. They both are able to play backup outfielder. If their batting is roughly equivalent, then Caleb Roberts playing backup catcher and first base may be better for the team than Jace Peterson playing second base and third base.
  • Looking several years ahead, there are four additional strong candidates for backup catcher: Adrian Del Castillo, JJ D’Orazio, Christian Cerda, and David Martin.