Teams are running wild on the Mariners (again); how will they adjust?
Meanwhile, the Mariners are running up(that)hill
With the first full month of the baseball season coming to a close, it’s time to take stock of some early returns. Especially of interest is stolen bases, now in the third year of the rule changes designed to create more interest on the basepaths. Mike Axisa at CBS Sports found that stolen base attempts are up over a percentage point from last season at this time, with no decrease in success rate, and as Ben Clemens at FanGraphs points out, the swipes will continue until success rates decline.
For the Mariners, however, that means another season of watching opposing teams run wild on them. Cal Raleigh has been the 10th-most run-on catcher in MLB so far this season, with 13 attempts made against him; so far, he’s only thrown out two runners, which is actually just slightly under what Statcast estimates as “Est. CS%”, or what the expected caught stealing is based on a league-average catcher (15% vs. 17%). Cal also saw the most attempted steals against him in baseball in his Platinum Glove season, but he was able to cut down 26% of runners last season, outperforming a 21% expected success rate. Raleigh has been down a tick in his arm strength metric so far this season, dropping ten places on the leaderboard from Top-10-adjacent among all catchers to 23rd, but otherwise, things appear to be following the trend set last year.
What is the cause for so many teams running heavily on Platinum Glove-winning Cal Raleigh? The old baseball aphorism is bases are stolen off the pitcher, not the catcher. The Mariners pitching staff as a whole has the seventh-slowest pace to the plate in MLB, at an even 19 seconds between pitches, with the chief offender being Logan Gilbert; however Bryan Woo and Bryce Miller both rank in the top 10 for slowest to the plate. That’s about where they were last season, at the same pace to the plate, which over the course of a full season had them as the third-slowest staff to the plate in MLB (Gilbert had the 12th-slowest pace; Bryce Miller and, surprisingly, George Kirby were back-to-back at fifth and sixth place, respectively). This tracks with the eye test, as there are many times this season where Raleigh has simply had no chance to throw out runners, sometimes not even attempting a throw. The Red Sox ran wild on Miller yesterday, swiping bags seemingly at will.
At this stage of the season, with the starting staff largely unchanged from last season, it’s not unreasonable to expect that teams will continue to run on the Mariners; it will be the job of Cal Raleigh and the coaching staff to manage the situation as they did last year. This has been a particularly challenging slate of teams to play, as well, as so many teams the Mariners have faced on this road trip are high-contact, low-strikeout teams that put the ball in play, making those extra ninety feet especially valuable.
The Mariners have attempted to counteract this by being aggressive on the bases themselves. Despite some frustrations—no runner has been caught more than Dylan Moore, who’s been cut down four times against five successful steals—the Mariners actually rank seventh in MLB in net bases gained while being the second-most aggressive team in baseball at taking advantage of stolen base opportunities, trailing just the Rangers. But that positive mark is largely due to the contributions of one player.
The most productive Mariner on the basepaths might surprise you, as it’s not a prototypical speedster: Randy Arozarena leads the team in net bases gained, with four (good for 13th-best in MLB). The least productive Mariner on the basepaths probably won’t surprise you: Miles Mastrobuoni has produced negative value through a combination of being very aggressive in his opportunities (fourth-highest attempt rate on the team) yet getting caught often. No Mariner has run more than Dylan Moore, whose attempt rate of 7.8% is seventh-highest in baseball, but it’s a risk that has only paid modest dividends, as DMo has gained five bases but also created three outs.
At this stage in the season, it’s still early to make any sweeping generalizations, but it’s already glaringly obvious how much the loss of Victor Robles hurts the Mariners if they remain committed to this level of aggression on the bases. Arozarena has been productive, largely because his risks are calculated, but he doesn’t have the first-step explosiveness that makes Robles so elite on the bases. Julio Rodríguez is an explosive runner, but simply isn’t on first base enough to make an impactful difference there (and stealing third remains a risky proposition). Ben Williamson has plus speed, but it’s unclear yet how that will translate at the big-league level. Mastrobuoni and Moore might see their numbers level out over the season, and both have been productive at getting on base to start with, but the early results have been mixed.
In an offensive environment that encourages and rewards stolen bases, it would be short-sighted of the Mariners to abandon their early aggressiveness on the bases entirely, but the fact remains that this is a very different team on the bases without chief speedster Victor Robles, and—like Cal and the pitching staff—that’s something that has to be adjusted to as the season wears on.