Lay off the high ones, Mark Vientos

Mark Vientos is a mess. You didn’t need me to tell you that, but that doesn’t make it any less frustrating. There isn’t anything novel about a player struggling in his second year in the majors, of course. Still, just take a look at the percentile rankings summary on his Baseball Savant home page. It’s blue (lowest percentiles) as far as the eye can see, and it’s especially glaring when contrasted against all the red (highest percentiles) in his profile in 2024.

His walks are up and his strikeouts are significantly down, but that’s essentially the only positive thing to take away from his performance compared to last year at this point. What jumps out immediately and definitively is that he’s been seemingly sapped of power compared to last season, and the approach and outcomes bear this out.

The first things to note include the standard assessments of both his approach at the plate and the outcomes of that approach. Despite some minor and moderate differences, his plate discipline hasn’t completely diverged from last season. In fact, he’s actually making more contact this year on pitches in the strike zone than last year. The problem is that the contact he is making has been of an extraordinarily low quality.

His batted ball profile illustrates a hitter that’s been putting the ball in play to the opposite field more often, particularly fly balls. His quality of contact is in the gutter with a significant decrease in Barrel % and increases to Weak % and how often he gets under pitches. For what it’s worth, his bat speed has decreased a tick this year as well. Compared to 2024, he simply looks like a completely different hitter.

Has there been any change to how pitchers approach him this season? The expectation should generally always be yes, especially following a breakout year. Let’s take a look at how Vientos fared against specific pitches both in 2024 and 2025 per the charts below courtesy of Brooks Baseball.

Two things to note here (besides a complete lack of power against breaking balls this season) are that he feasts on changeups and that the drop in his BABIP against hard stuff this season is pretty striking. To seemingly counteract the former, there’s been a sharp decline in the percentage of changeups he’s seen so far this season. He saw it 10.6% of the time in 2024 and so far just 5% of the time this season. The latter could potentially be at least partially explained by both a regression to the mean and the next set of charts also courtesy of Brooks Baseball. The first two are zone profiles for the percentage of swings he took against all pitches in 2024 and so far in 2025.

There’s a pretty significant increase in the amount of swings he’s taking on pitches up and up-and-in outside of the strike zone when compared to last season. The charts below present similar data, but focused on only hard pitch types.

It’s apparent that the league decided that they don’t believe he can lay off heaters up and out of the zone, and boy is he biting. This dynamic would go a long way in explaining the poor quality of contact, the increase in harmless flyballs, and the fact that he seems to consistently be getting under the ball.

We probably shouldn’t go quite as far as saying it should have been expected that Vientos would struggle in year two, but it’s not all that surprising given what typically occurs during sophomore seasons for many players. There are other players in the lineup who likely deserve more scrutiny given their service time and performance thus far, but Vientos is the one with someone on the cusp of overtaking him and snagging his role on the team.

It’s easy to sit back in an arm chair and say a player should just stop doing something, and it’s possible there are other issues that have contributed to Vientos’ struggles this season. He’s been battling injury and there’s always the possibility of some underlying mechanical issue, for instance, but simply laying off of the stuff at his chin would be a step in the right direction.