Jeff Passan's prediction for Mariners' Logan Gilbert is not as crazy as it sounds

If there's ever a time for pitchers to start throwing new pitches, it's spring training. Refining grips, delivery, and pitch shape take time, but the preseason allows hurlers to test their stuff in live reps without any real consequences. Logan Gilbert has already been toying with new fastball variants but experts like ESPN's Jeff Passan believe a splinker could be in the works as well.

Logan Gilbert has experimented with the splinker this spring to impressive results

In a preview of the Mariners' season, Passan wrote that he wouldn't be surprised if Gilbert "becomes the latest pitcher to master the splinker" and he's not the first to point this out. Michael Rosen of FanGraphs also mentioned it in an article discussing new pitches debuting in spring training and described it as sitting around 93 mph and having "crazy depth."

Because of its hybrid nature, Statcast currently classifies all splinkers as sinkers, even for pitchers like Jhoan Duran and Paul Skenes. Assuming the four sinkers that Gilbert has thrown in spring training thus far are indeed splinkers, it looks like a happy medium between his current four-seam fastball and splitter.

Similar to the motivation for adding a cutter, adding a splinker creates a new fastball variant that can tunnel off of his heater with some added arm-side movement. Because it also resembles a splitter, it can catch opposing hitters off guard thanks to its added velocity, theoretically making both pitches more effective.

Part of the reason that Gilbert seems intent on adding a new pitch could be that his stuff in 2025 wasn't as sharp as it was in 2024. His slider had a pitching run value of 14 in 2024, making it the most effective pitch in his arsenal and one of the best sliders in MLB. Last year, it was worth negative run value thanks to a .510 opposing slugging percentage. For now, he's still seen as the team's ace but Bryan Woo isn't far behind.

He may also have been affected by the flexor strain that limited him to just 25 starts last year, but it's still better to be proactive about getting back to pitching at an elite level. Since he still has another year of arbitration and is slated to hit free agency after that, it's never too late to build up his market value.

The Mariners have always encouraged their pitchers to try new things and it's a major reason why their arm talent has been so successful in recent years. Logan Gilbert is talented enough to be able to acquire new pitches quickly and make them work. Perhaps he'll opt for the cutter, perhaps he'll choose the splinker. Regardless of which pitch ultimately sticks, he still has a real chance to be one of the most dominant starters in baseball.