A common practice in baseball analysis is to compare the current season to past iterations once we reach a certain threshold. A hitter’s plate appearance total, for example, is a popular measurement. Innings from a pitcher is another frequently cited. For 2021 purposes, however, it isn't easy to do that reasonably. The 2020 season itself was a glorified small sample, more or less. The campaign still counted, yes, but it was hard to take away too much significance from the numbers in the middle of a pandemic.
But thanks to advancements in how the game is tracked, we can also pick apart particular batted ball events, plate appearances, or pitches thrown to such great detail for analysis purposes. Even if the final results aren’t completely trustworthy, we might be able to identify trends worth monitoring. This is a key component of analyzing baseball in 2021 compared to the chaos known as 2020.
One trend that I’ve been monitoring for the past couple of weeks is Michael Brantley’s plate discipline. Specifically, it pertains to how much the veteran slugger is chasing pitches outside of the strike zone.
If the season concluded today, Brantley’s 28.9 percent chase rate this season would be the highest in his career. Compared to last season at 20 percent, even in a small sample year, there is clearly a change. And that increase is across all three pitch groups as Baseball Savant defines (Fastball, Breaking, and Offspeed). Brantley's recent tendency has been to chase more in a similar number of plate appearances between 2020 and 2021.
From there, I would normally expect a hitter to have an increased strikeout rate if he is chasing more outside of the strike zone. However, Brantley’s strikeout rate has actually decreased from last season, and the metric only requires about 60 plate appearances to achieve increasing reliability. This development indicates that while he is chasing pitches at a higher rate, Brantley isn’t missing as much as he did last season. Sure, enough that is the case based on the graph below.
Of the three pitch groups mentioned earlier, the most notable decline in his chase and miss rate occurred when Brantley saw breaking pitches, down from 60 percent in 2020 to 20 percent in 2021, with roughly the same number of breaking pitches thrown in each of the two seasons. The interesting part is that Brantley isn’t hitting the breaking pitch as well as he did in past seasons with a .261 wOBA thus far. In his last full season in 2019, that wOBA was .346. Of course, we’re still working with a small sample as we’re only into the third week of May. Also, I should note that Brantley’s contact rate on pitches thrown outside of the strike zone (o-contact) is now at 84.2 percent, which is noticeably higher than his 80.8 percent career mark. So, yes, Brantley is chasing more but making more contact. They don't call him a “professional” hitter without reason.
But when we zoom out to pre-pandemic seasons, there is a larger, albeit disturbing, trend to monitor. That increase in outside contact this season has come at the expense of his 5.1 percent walk rate, which would be the lowest mark of his career by far. Plus, that lowered strikeout rate I touched upon earlier would still represent a jump over his career average by about 2.4 percent. It is also interesting that Brantley’s contact rate on pitches thrown inside the strike zone (z-contact) has gradually decreased from his peak. While his 89.6 rate this season represents an improvement from the 86.1 percent rate from 2020, it remains lower than his 90.9 percent career z-contact rate.
To summarize, Brantley is chasing more outside of the strike zone — and missing less — to adjust to a growing issue inside of the strike zone. The inside of the strike zone part will require further analysis, but it remains fascinating to see how one trend can help point you in the direction of another. Stay tuned.