Patrick Sandoval Is Walking A Fine Line With Red Sox After Two-Year Hiatus

After over two years on the injured list, Patrick Sandoval made his long-awaited return to the major leagues on July 6 when he pitched 4.1 innings against the Chicago White Sox. Signing with the Boston Red Sox in the 2025 offseason, he spent the previous six seasons with the Los Angeles Angels, where he showed high upside as a starter, but saw his production limited by injuries and late call-ups. Eventually, his 2022 breakout season was his first full season in the majors, where he posted a 2.91 ERA and 3.09 FIP in 148.2 innings and recorded a career-high 151 strikeouts.

Since returning from injury, Sandoval has been a solid addition to the Red Sox's rotation, compiling a 3.30 ERA and striking out 29 batters in 30 innings. He has consistently ramped up his pitch count in each appearance, with Boston winning in five of his six starts. While he has found early success with his signature changeup, with opponents hitting only .148 against it, Sandoval still needs to improve other areas of his arsenal if he hopes to return to his 2022 form.

Patrick Sandoval's Slider Is His Missing Ingredient

While his changeup has been his most effective pitch throughout his career, Sandoval has favored his slider this season, throwing it 29.6% of the time. To date, the only other season in which the slider was his most-used pitch was his 2022 breakout season, when opponents hit just .201 against it. However, this season, that average has jumped up to .269, with Sandoval's command appearing to be the biggest difference.

Looking at what made the pitch so successful in 2022, Sandoval consistently spotted his slider low or out of the strike zone on two-strike counts, generating a 33.6% whiff rate. His consistency with locating the pitch resulted in a career-high 42.0% chase rate and a 26.9% put-away percentage. This season, Sandoval is attempting to recreate that approach, increasing his slider outside-zone rate from 52.0% in 2022 to 57.5%, yet the results haven’t been the same. In 2026, the southpaw has been less consistent with his spotting, often leaving pitches high in the zone or exaggerated out of the zone. As a result, batters have been less fooled and are chasing the pitch at a career-low 27.5% rate, while his whiff rate has dropped to 30.8% and put-away percentage to 19.4%.

The ineffectiveness is especially noticeable when comparing it to his changeup. While its 41.3% whiff rate is down slightly from 44.5% in 2022, Sandoval's put-away percentage has surged from 24.4% to 40.0%, a stark contrast to the effectiveness of his slider. In layman's terms, Sandoval’s ability to deceive batters hasn’t just gone away, as his changeup continues to finish at-bats and generate swings and misses at a higher rate than in 2022. He just needs to be more consistent with his location.

The lack of command with the slider is especially daunting given Sandoval's history of having a high walk rate. This season, he has walked batters at a 9.2% rate and has posted a rate north of 9% in all but one season of his career. If hitters continue to lay off his slider outside the zone, Sandoval could find himself in deeper, more unfavorable counts and ultimately allow more baserunners. It's in those spots where he falters, and one blow-up outing or two could change the tune around his standing with the Red Sox.

For now, he's become an integral piece of the rotation, covering valuable innings in the wake of injuries and trades that have depleted the team's depth. If he can tighten the spread on his favorite pitch, he might even earn a start or two in the playoffs.