Amazing stat highlights Red Sox rookie Triston Casas’ plate discipline

The Red Sox rookie has shown impressive patience at the plate

It only took a few weeks of adjustments for Boston Red Sox rookie Triston Casas to really get the hang of major-league pitching.

Casas delivered a pair of hits, including an RBI double, in Thursday’s win over the Baltimore Orioles. He’s riding a four-game hitting streak and has at least one hit in seven of his last eight games, raising his average to .213. This marks the first time that Casas has cracked the Mendoza Line since going 1-for-4 in his major league debut.

While the batting average remains underwhelming, Casas has been getting on base at an elite clip by piling up walks. His .385 on-base percentage would lead the Red Sox and rank eighth in the majors if he had enough plate appearances to qualify.

According to Stathead, only 16 MLB rookies have walked 17+ times in the first 22 games of their career in the Expansion Era (since 1969). Casas is the first to join the list since Jake Bauers in 2018.

With 17 walks and 17 strikeouts, Casas joins exclusive company with a walk percentage that is identical to his strikeout percentage. His 21.8 BB% leads the majors among hitters with 75+ plate appearances this season. Among qualified hitters with at least a 10.0 BB%, only four have a strikeout rate that is equal to or lower than their walk rate – Alejandro Kirk, Alex Bregman, Yandy Diaz and Juan Soto, per FanGraphs.

The 21.8 K% remains a bit high but not alarmingly so. There are over 50 qualified major league hitters with a strikeout rate of at least 22.0% this season. Casas has only struck out three times in his last six games, putting to rest some early concerns about his ability to make contact.

Hitters who draw walks at least as frequently as they strike out are a dying breed in the modern game. Casas’ inclusion in this exclusive group comes with the caveat of a small sample size. However, his approach at the plate indicates that he should continue to draw walks at a high rate while preventing his strikeout rate from spiking.

Casas has an uncanny eye for the zone. He rarely chases pitches that aren’t strikes, swinging at only 16.4% of pitches outside of the strike zone. His 16.4 O-Swing% would lead the majors if he were a qualified hitter. Casas is a patient hitter willing to take pitches. Juan Soto (35.1 Swing%) is the only qualified hitter who swings at a lower percentage of pitches than Casas (36.0 Swing%).

His early struggles stemmed from a lack of contact on pitches inside the zone. A willingness to take pitches can at times work against him when borderline calls don’t go his way. That’s unavoidable with his patient approach. However, Casas was also missing pitches he had to swing at since they were in the zone. There’s a learning curve with making the leap from Triple-A to the majors. Casas needed time to adjust to the higher velocity of fastballs and the sharper movement of breaking balls that he’s facing compared to most of the competition he faced in the minors.

Casas has shown improvement in that area. While his contact rate in the zone was trending toward being among the worst in the majors, his 83.7 Z-Contact% has climbed out of the bottom-30 (based on qualified hitters).

Making more contact is bound to lead to better results as the sample size expands. Casas has seen his batting average rise from .079 to .213 over his last eight games. He has smashed three home runs over that span, showing his ability to make hard contact.

Casas arrived in the big leagues with a reputation for his strong plate discipline and he’s backed it up with his impressive approach to begin his career with the Red Sox. While some will still harp on the meager batting average, his excellent OBP, strikeout-to-walk ratio and ability to make hard contact foreshadowed that better results were coming and we’re starting to see that come to fruition as Casas heats up down the stretch.