Whether you think it's merely a gimmick or a pitch too erratic to control with sustained precision, the knuckleball engenders strong opinions. Most of the writing covers specific practitioners, like Henry Druschel's piece on Steven Wright, while a subset of it attempts to appreciate the mechanics. What I would like us to focus on instead is its lasting effect, its fallout. Something Scott Spratt called a "Knuckleball Hangover."
Spratt compared the spread between a batter's season long average and wOBA to their numbers in the days following their games versus knuckleballers. Here's what he found.
In sum, the day after knuckleballer games, hitters demonstrated a decrease between six points of batting average and 12 points of wOBA that lasted longer than typical deviations from their season long average. He specifically wanted to apply his learning to fantasy baseball and concluded that while this potentially counts as evidence for a knuckleball hangover, it is statistically irrelevant within the realm of fantasy sports.
Although his results aren't impactful for rotisserie players, they may be for actual Major League players and managers. Furthermore, if there is an actual lasting effect imposed on batters from facing a knuckleballer, there may be a way to enhance it. For example, if batting average suffers team-wide following a match against the knuckleball, then a knuckleballer's placement in the rotation becomes even more impactful. Pressing further, do batters have a more difficult time facing the fastball or curve (or whatever the number one pitch is for the next day's starter) following a match with, say, Steven Wright? If so, maybe high WHIP/high strikeout pitchers like Chris Archer might benefit from having opposing lineups primed by a knuckleballer first.
Over this series we'll look at three things. First, we will set the table by exploring what exactly a knuckleballer is disrupting. Second, we'll look at launch angles prior to, versus, and the game(s) following a bout versus the knuckler. Third, and finally, we'll look at plate discipline.
Let's start by granting the following assumption:
Professional athletes are creatures of habit - from superstitious socks to pregame warm-up rituals; patterns contribute to their success. In basketball you can watch the rhythm of a jump shooter; in golf the rhythm of a tee shot. Years of practice and gameplay have ingrained themselves on their instincts. It is rhythm, familiarity, which allows an athlete to get out of their heads and react with the elite precision they've cultivated over thousands of hours.
Here's the hypothesis: A "knuckleball hangover" exists by throwing off a batter's rhythm, inclusive of both pitch identification and swing, that batters perform below average in at least their next game.
Neurology supports the hypothesis. The human mind, as it repeats a task, seeks out and then sticks to the most energy-efficient way to produce satisfactory answers. Batters are human, but they are humans with a twist because their minds have been exceptionally trained to discern how a spinning little ball being thrown at them from 60 feet and 6 inches away can be crushed with a piece of wood.
Below is a table breaking down the league's pitch usage by type. This includes pitchers whose primary pitch is the knuckleball. Another way to look at the table is as a breakdown of a batter's season-long routine in the batters box.
If batters play 99.50% of a typical full-time player's season is spent not dealing with the knuckleball then a sudden inversion might be enough to mess with the pitch identification process for a few at bats over the next game or two.
A lot of theories can be made to fit any given set of data, however. There are some caveats that ought to be stated before moving forward. First of all, I'm clearly generalizing. Mike Trout seems less likely to suffer from a knuckleball hangover than 'His Strikeout-ness' Chris Carter or relative nobody, Brandon Nimmo.
Second, since we are working on a league-wide aggregate and general knuckleballer scale, it is possible that other factors explain the effects better or that one knuckleballer in particular was so much more effective than the others that he accounts for the entire effect himself. According to wFB data, when Steven Wright throws a fastball he does it with significantly more efficacy than R.A. Dickey. Maybe the mixture of two effective pitches is to blame more than the knuckleball alone.
The last caveat is that the incomparable Eno Sarris, a month ago, demonstrated that the knuckleball is actually a more conventional pitch than we typically take it to be. He closes with a line, though, that hints at what it is about the knuckleball that might potentially have a short-term enduring effect on batters' mental processes. The knuckleball "is a little bit like every pitch, actually. You just don't know which one it will be, and that's the genius of it."
However if there is an actual effect, an actual hangover that trickles into the following game, it would make sense to see it in either (or all of) the plate discipline and launch angle data. Major league players adjust quickly - it is part of what makes them elite players. Swing and plate discipline are how the do that. So that's what we'll look at next time.
Until next time...
Steven Demmler is a contributing writer at Beyond the Box Score. He can be found on Twitter at @sedemmler.