Mariners rookie Jose Caballero pushing for extended big league stay

Rookie infielder Jose Caballero’s initial call-up to the Mariners’ roster was expected to be a short-term stint to provide some depth while utilityman Sam Haggerty dealt with a concussion, but he’s parlaying that opportunity into a larger role. Ryan Divish of the Seattle Times writes, he’s already made a strong impression on manager Scott Servais.

“From the day he showed up here, he was not in awe of anything,” Servais said of Caballero, going on to praise the 26-year-old’s baserunning, on-base ability and defense. “He understands how to play and he doesn’t back off.” 

President of baseball ops Jerry Dipoto had similar praise, telling Corey Brock of The Athletic that Caballero “has been terrific in every way.”

Caballero has indeed impressed, surging out to a .276/.321/.431 batting line with a pair of homers, three doubles and six stolen bases in six attempts through his first 24 games (70 plate appearances). He’s had a bit of good fortune on balls in play (.333), but even if his average took a slight step back, an 11.4% walk rate would keep his on-base percentage plenty strong.

The plate discipline hasn’t been a small-sample fluke, either. Caballero has a career 13% walk rate in the minors and has chased pitches off the plate at a lower rate than the average big leaguer in his young career. Statcast also credits him with 92nd percentile sprint speed, so there’s good reason to believe he can keep swiping bags at a high rate of success.

Caballero’s immediate strong play further shines a light on the mounting struggles of veteran second baseman Kolten Wong, whose .177/.259/.208 batting line (40 wRC+) ranks among the worst in baseball. Wong’s 20.4% strikeout rate is the worst of his career, and he’s making hard contact at career-worst levels as well (85 mph average exit velo, 24% hard-hit). Statcast ranks Wong in the fifth percentile or lower in hard-hit rate, average exit velocity, barrel rate, expected batting average, expected slugging percentage and expected wOBA. His once plus sprint speed is down to the 37th percentile as well.

In the wake of such a miserable start to the season, Wong has already begun to cede time at second base to Caballero. The rookie has made five starts at second base since Wong’s name was last penciled into the starting lineup. Wong has been on the bench, but the Mariners will have to figure out how to align their infield and bench mix soon. Mariners GM Justin Hollander told reporters Monday that utilityman Dylan Moore could be reinstated from the injured list during the team’s current homestand, via Divish.

Moore, who over the winter signed a three-year, $8.875M contract that bought his final arbitration seasons and one free-agent year, has yet to play in 2023 due to oblique and core injuries. He’s played in four minor league rehab games, however, and the team apparently believes he could be back on the big league roster with only a few more. The current homestand runs through May 31.

The 30-year-old Moore has had an up-and-down run with the Mariners since debuting in 2019. He’s a career .208/.317/.384 hitter, though as evidenced by a .255/.358/.496 showing in 159 plate appearances in 2020 and a .224/.368/.385 line in 255 plate appearances last year, he has plenty of on-base ability and some pop in his bat. Moore has 35 home runs and 65 steals in 381 career games, and he’s drawn outstanding defensive ratings at second base, third base and in both outfield corners.

Seattle’s bench currently consists of backup catcher Tom Murphy, the aforementioned Haggerty and struggling veterans Wong and AJ Pollock. Barring an injury elsewhere in the lineup, it’s likely someone from that bench group will be displaced by Moore’s return. Haggerty has minor league options remaining, and that route would preserve more depth, but he batted .256/.335/.403 last season in 201 plate appearances, showing plenty of defensive versatility. The Mariners will have to weigh that against the poor starts of both Wong and Pollock in determining their preferred course of action.

The Mariners are also anticipating a return to health for some important bullpen arms, via Divish. Closer Andres Munoz and righty Penn Murfee are both expected to join the Mariners on their upcoming road trip, which runs from June 1-11. Munoz has been throwing bullpen sessions, and Murfee has responded well to a platelet-rich plasma injection. Both will need quick tune-ups on minor league rehab stints, but they’re only a matter of weeks away.

Munoz, 24, broke out as one of the best relievers in baseball in 2022 when he pitched to a 2.49 ERA with a stellar 38.7% strikeout rate against a 6% walk rate. He averaged a whopping 100.3 mph on his heater, and his 21.6% swinging-strike rate trailed only Edwin Diaz among all big league pitchers with at least 50 innings pitched.

Murfee, meanwhile, has pitched 82 1/3 innings of 2.73 ERA ball dating back to last year’s MLB debut. He’s fanned 27.9% of his opponents against an 8.3% walk rate without displaying the type of platoon splits that many fellow sidearmers tend to carry. Lefties have batted just .210/.297/.305 against Murfee, while right-handers have posted an even more dreadful .165/.232/.303 slash.