Jackson Merrill Needs A Better Approach Against Fastballs

The San Diego Padres have gotten off to a hot start, owning a 19-9 record and sitting second in the National League standings. While the narrative surrounding their offseason focused on them losing key arms with Dylan Cease and Robert Suárez both leaving the team in free agency, their pitchers have actually been the catalyst for their early season success. As a unit, San Diego’s pitchers have produced the second-best 3.56 FIP in the league, anchored by closer Mason Miller, who has only allowed two runs in 14.1 innings. 

While the pitching staff has delivered, the Padres are still waiting for their offense to catch up. Despite their strong record, they rank below league average in both batting average (.240) and OPS (.693), due in large part to slow starts from key contributors. Fernando Tatis Jr., Manny Machado and Jackson Merrill hold three of the four largest contracts in the lineup, yet Tatis has been the most productive of the group with only a .257 batting average and no home runs. While Machado has struggled, batting .232, Merrill has experienced the steepest drop-off, posting the fourth-lowest wRC+ on the team at 79 and showing significant regression in this third season.

Merrill has consistently hit in the heart of the Padres lineup, batting third or fourth, yet has produced a -4 batting run value while slashing .213/.280/.352 with a .632 OPS. However, despite the slow start, his underlying metrics suggest his raw ability remains intact. Merrill still produces a 11.3% barrel rate and 45.0% hard-hit rate that both rank well above average. The power hasn't disappeared; the difference lies in his approach.

Merrill has always been aggressive at the plate. Last season, he led the team with a 45% first-pitch swing rate and that has carried over to this year at 47.4%. A slight increase, but it is notable when looking at the balls he's swinging at. While his in-zone swing rate has increased to 82.9%, the highest on the team, his chase rate also sits at 37.9%, the second-highest on the roster. While this aggression isn’t anything new, his lack of contact is. This season, Merrill ranks near the bottom of the team with a 78.3% in-zone contact rate and owns a 28.5% whiff rate, placing him in the bottom-third of all qualified MLB hitters. 

The significance of the drop-off becomes even clearer in the context of the pitches he's seeing. Four-seam fastballs account for 36.1% of the pitches he faces, and they'e starting to eat him up. After posting a +7 run value against four-seamers last season, he has dropped to a -3 mark, a sharp decline that points to timing issues and may explain why his aggressive approach has been so inefficient.

However, Merrill isn’t completely broken. While he has struggled against four-seamers, he has fixed a big gray area in his game and that is his production against sinkers. After posting a -3 run value against sinkers last season, he has turned it into one of his strengths, improving to a +2 mark. Perhaps, then, even more than a velocity issue, this comes down to where he's being attacked. Four-seamers have more perceived rise, hence why they're so effective up the in zone; sinkers, meanwhile, are often used to target hitters low.

That's a lot of high fastballs. Even with a faster swing speed this year, it'll be hard for Merrill to do damage on those pitches if his timing is off.

I'll repeat: Merrill isn’t broken. In many ways, he isn’t far off from the hitter he’s been in recent seasons. The power remains, and the underlying metrics suggest a correction is possible. But a change in his approach will be needed, lest he continue to get eaten alive by fastballs.