Geraldo Perdomo’s metrics paint him as a middling SS. Why are we so afraid to pivot away from him as an everyday player?
Geraldo Perdomo is a fan favorite on the Diamondbacks these last two years, and spending just 10 minutes watching any D-backs game would show you why. Guaranteed within that 10 minutes, the camera will find Perdomo and his bubbling personality bouncing around with childish joy. But when you strip away the joy and just look at the cold, hard numbers, Perdomo is…okay. Among SS with at least 750 at bats between 2023-24, Perdomo ranks:
- wRC+: 17th
- WPA: 10th
- wOBA: 15th
- Defensive Runs Above Average: 18th
- fWAR: 18th
Those are fine numbers, but certainly could be looked at as something that could be improved on. Despite the presence of a Top-10 Prospect in all of MLB waiting in Reno to take over the everyday shortstop position, many Diamondbacks fans (and the organization’s Front Office) are hesitant to move Geraldo Perdomo off his everyday duties in favor of the talented ROY candidate. Why is that?
One quality that Perdomo has exhibited which endeared himself to fans is his ability to put together good at bats. Last year, I created a statistic that was a fun attempt to quantify “peskiness” as a hitter and Geraldo Perdomo was the best in all of baseball at it in 2023. I wanted to revisit that stat again in 2024 and see how Perdomo measured up. Here’s how he fared:
Perdomo chased a little more than last season and he saw a fraction less pitches than in 2023, but he offset that by whiffing less and ended up posting a nearly identical Pesky score of 77% better than league average. While his score of 178 was good enough to lead MLB last season, his mark of 177 was second best in all of baseball this year* (among players with at least 350 Plate Appearances). His ability to extend at bats and not swing at bad pitches is a skill he’s proven to maintain and not a fluke. And no, Perdomo did not get extra credit for homering off Pesky Pole.
Geraldo also found himself in rare air with his ability to outperform his ‘expected’ statistics. One of my go to metrics to measure overall offensive effectiveness is wOBA which takes the average run value of each plate appearance and values it on a scale similar to OBP, a slightly more accurate way of measuring offensive performance than just OPS. Geraldo Perdomo’s wOBA was right around league average at .317 but that’s not the interesting thing. His xwOBA (which calculates what his wOBA should be based on his quality of contact) was .280, a gap of nearly 40 points! For context, the eight other Diamondbacks with at least 350 PA all finished within at least 15 points of their xwOBA.
Every year there are players who overperform and underperform their expected statistics by large amounts, so Geraldo Perdomo’s 2024 isn’t all that special in that regard. However, when you look at his 2023 and 2024 together, he outperformed his xwOBA each year by a significant amount (44 points in ‘23). How rare is that? Since 2021, only two other players have outperformed their xwOBA by 30 points in consecutive seasons (Randy Arozarena in 2021-22 and Jose Altuve in 2022-23). No one has outperformed by such a large margin in 3 out of the last 4 years regardless of whether it was consecutive or not, so perhaps there is regression coming, but maybe Perdomo’s approach to hitting lends itself to him squeezing the most out of every at bat?
What about his defense? He’s never really looked to me like a Gold Glove caliber defender at the most important defensive position on the diamond, and the metrics are split on how good of a defender he actually is. Where he has impressed me and many in the SnakePit community is his innate ability to feel everyone else on the field, particularly when it comes to identifying when the pitcher could use a blow and coming in to call his own impromptu mound visit.
Put all of this together and it’s a whole lot of stuff that doesn’t really make it into the box score or the WAR calculation, but the team just feels different when Geraldo is out there. With Perdomo at the bottom of the order, you always feel like a RattleRally is right around the corner. When he’s bouncing around the infield dirt, you feel secure in knowing the plays that have to be made defensively will be made. How can you justify moving off of that?
That leads me to the question that I was asking at the beginning of 2024 and has got even harder to answer in 2025: How good does Jordan Lawlar have to be to move Geraldo Perdomo to a utility role?
In the most simple of measures, Geraldo Perdomo was quantified as being worth 2 wins above a replacement level player (per FanGraphs), enough for 23rd among primary shortstops. Yes, he had an injury shortened season, but no one played twice the games or had twice the Plate Appearances, but 9 shortstops in MLB had over twice the fWAR. Could Jordan Lawlar be at least a middle-third SS in MLB in 2025? Given his immense physical tools, I’d say probably so. But what about the non-physical tools? The intangibles? Does Lawlar have the it factor that Geraldo so obviously has an 80-grade in? If not, how good does he have to be in order to offset the loss of intangibles?
Let me put this another way. What shortstops would you take over Geraldo Perdomo today? The MVP candidates (Witt, Gunnar, Lindor, Seagar) I think are an easy Yes. What about the All-Star caliber SS like Elly, Swanson, Turner or Tovar? That starts to get a little tougher. In raw ability and measured outcomes, they all probably have an edge over Perdomo, but Gerry’s effect on the entire club is special. Something that we can’t properly quantify.
To my eye, there is only one Geraldo Perdomo. He may not rack up WAR, but he is a classic greater-than-the-sum-of-his-parts player. He is an engine for this team, and that’s not something that can be easily replicated by a rookie, no matter how talented. Could Lawlar have more WAR than Perdomo if given the same opportunities in 2025? Could his bat fit closer to the middle of the lineup than the bottom? Is his defense a little more flashy? I’d say probably so to all of those questions. But would the Diamondbacks be better in 2025 if they were to replace Perdomo with Lawlar? Interestingly, I’d say probably not. There’s just something about Gerry.
*If you are wondering, the Pesky+ metric is a pretty sticky statistic. Eight of last season’s Top-Ten in Pesky+ finished in the top 12 in the metric in 2024. As a brief reminder, Pesky+ takes the percentage of pitches whiffed and swung outside the strike zone on, scales it by how many pitches the batter sees per Plate Appearance. A score of 100 is league average, 110 would be 10% better than average and 90 would be 10% worse. If interested in how other Diamondbacks (or any players) fared in 2024, let me know in the comments.