Triston Casas Is Thumping in Boston

Things didn’t look so hot for Triston Casas in the first few months of the season. From the beginning of the year through the end of May, he had a 95 wRC+ and a .195/.326/.376 slash line. He wasn’t doing enough damage in the heart of the zone and had a suboptimal launch angle distribution. That’s a fancy way of saying he wasn’t consistently making pitchers’ mistakes hurt because his batted balls were all over the place. His promising future as a masher had a bit of a cloud over it, but after an explosive July, there is good reason to be more confident in him.

Casas’ turnaround has multiple layers to it. Along with a slight mechanical tweak, he has taken on a more aggressive approach while focusing on contact towards the middle of the field. With a solid combination of power and natural lift, he is able to play with the big parts of Fenway Park. He isn’t utilizing the approach we’ve seen many lefty Red Sox hitters adopt over the years of peppering line drives and fly balls off the Green Monster. In fact, he’s 134th out of 143 qualified hitters in Oppo%. Instead, he sticks to where his bat path plays – the middle of the field. Well, that was his approach in July, anyway. Below is a table showing Casas’ horizontal and vertical batted ball profile by month this season:

He had a good June, but in terms of his batted ball profile, it didn’t look like his breakout July. In July, he stayed off the ground at an extreme rate while hitting half of his batted balls up the middle. There are only three qualified hitters in baseball with a groundball rate below 30% for the entire year: Jack Suwinski (26.1%), Nolan Gorman (27.8%), and Mookie Betts (28.0%). This isn’t in the table, but Casas’ July HR/FB ratio was 29.2%, which would put him behind only Shohei Ohtani if he were to sustain it over the full season. To see Casas hit at rates similar to elite guys like Betts and Ohtani is both good and bad. He doesn’t have the raw power or hit tool to live in outlier territory on a consistent basis, but that doesn’t necessarily invalidate his success. Rather, it shows us what Casas needs to do to be a consistent power hitter. If his swing tweak and new approach enable him to more consistently hit the ball in the air, we should have greater confidence in his ability to sustain success, even as his stats become less extreme.

Before looking at the mechanical tweak, I want to focus on where and when the Red Sox first baseman has been more aggressive. The data below details his swing rates on pitches in the upper and lower third of the zone:

When the calendar flipped to June, Casas got significantly more aggressive at the top and bottom of the zone. As July rolled around, he doubled down on that aggression while adding more early count swings. There is an old school mantra that the best pitch you’ll see in an at-bat is the first one. Pitchers want to get ahead and take advantage of the hitter trying to find their timing. Still, if a pitcher lays in a cookie, the hitter should attack it. It’s always a sound approach to hunt the heart of the zone, and if you’re a struggling rookie, it makes even more sense to simplify things. When Casas implemented that strategy in July, it paid off.

He had success in the first two months of the season on 0-0 pitches in the zone, with a .424 and .681 xwOBA, respectively. In June, he ran a .026 xwOBA on these pitches across 18 total swings, though the results on those swings seem like a small sample blip; 11 of them were foul balls and three were whiffs. Something was off there, but the trend didn’t continue into July. Casas flipped the script and bumped up his swing rate by over 20 percentage points while running a .476 xwOBA. If a pitcher attacked him in the zone to start the at-bat, he put on an A swing. Now that he seems to have a better feel for his swing, he’ll have to strike the right balance of patience and aggression depending on how pitchers approach him.

Let’s look at the adjustment that helped things click mechanically. Here are a few swings from May and June before Casas made the change:

And here are a few during his stellar month:

Every hitter has a different feel for how to turn their barrel over and enter the zone. Some are more handsy, like Marcus Semien, while others aren’t handsy at all, like Casas. My use of two different angles from before his tweak is intentional. One shows his hands relative to his body on a straight angle, and the other shows how far he tucked them behind his ear. There was a good bit of movement that was triggered by his hands. But after his tweak, his barrel was almost perpendicular to the ground, with his hands working according to the movement of his entire upper body load rather than on their own. This brings me to the idea of connection. Before explaining what that means, take a look at this video posted by Alex Speier from a few days ago:

Triston Casas does not step in the bucket. He steps with a bucket. pic.twitter.com/z7TFNtM3EA

— Alex Speier (@alexspeier) August 4, 2023

This is a drill that hones the feeling of early connection between your upper body and barrel. By holding the bucket between his arms and chest throughout his swing, Casas establishes where his barrel is in space relative to his arms and torso. The result is his hands being along for the ride, rather than being the driver of the swing. In other words, his barrel placement is the result of how his upper body moves in space. While the swing in this video isn’t what it looks like in game, it helps give Casas the feel he needs to have an efficiently sequenced load and plane of rotation. You’ll notice that his hands are hardly moving during this practice swing. That ties directly to what we saw him change in July. His hands aren’t tipping until his shoulders do, and he’s not letting them guide his swing path. The result is improved barrel control stemming from better feel for where his barrel is in space. The data backs that up too. July was the first month Casas had a SweetSpot% above 37% on the season, and he blew that mark away, with 49% of his batted balls hit between eight and 32 degrees.

Usually, we don’t get a look into drill work like we did here. Connection drills are very common but can look confusing to the casual viewer. Luckily for us, a logical story can be told here. There is a direct line between Casas’ batted ball data and swing tweak, and the connection drill swings. I often talk about players finding their blueprint for success. A lot of the time, a particular drill can help a hitter get back in line with that blueprint. Casas now appears to have a better idea of idea of what that looks like for him, and specific cues for how he can stay there.

All this said, it doesn’t necessarily mean Casas has figured out hitting. Like most hitters, he has holes that can be exposed. As he finds success, pitchers will adjust their mix or location. Since August began, Casas has faced a career-high rate of breaking balls. He hadn’t seen more than 34% breakers in any month, but after 73 pitches this month, that rate is up to 50.7%. It’s working too – his whiff rate on that pitch group is 41.7% and he has yet to barrel a breaking ball. It’s a cat and mouse game that he will have to continuously adjust to while trying to find stability.

How Casas progresses versus his opponents’ changing approach will be crucial to our understanding of where his floor and ceiling will ultimately settle. At the very least, though, we’ve seen what the best version of Casas might look like, even if it hasn’t lasted a full season. A 122 wRC+ in your first full season ain’t too shabby.