"That’s what speed do." –
Winston Churchill Jarrod Dyson
A big part of the narrative around the Kansas City Royals' Wild Card game victory against the Oakland Athletics, centred around their ability to wreak havoc on the base paths, exploiting the noodle-armed Derek Norris. However, the catcher is but one of three actors that combine to determine whether a runner is successful in stealing a base. The time it takes the runner to reach the base he’s trying to steal and and the time it takes the pitcher to deliver the ball also play an important role in this equation. Interestingly, recent research by Max Weinstein (including research on this very site) suggests that the pitcher has more influence on the running game than the catcher.
Today, we’ll explore the pitcher’s side of this equation, considering how base runners behaved for each of the major league pitchers who qualified for the ERA title in 2014 (minimum 162 innings). In the figure below, the horizontal axis represents the percentage of times runners attempted to steal against the pitcher (SBA%). This is the number of attempts (stolen bases + caught stealing) divided by the stolen base opportunities (plate appearances with a runner was on first or second with the next base open). On the vertical axis, the more traditional stolen base percentage (SB%).
The scatter plot reveals a general, yet intuitive, correlation. Pitchers with a higher SB% also face a greater rate of steal attempts, with a relationship that is best described by a logarithmic trend line. Some pitchers, such as Scott Feldman, Tyson Ross, and A.J. Burnett are targeted more by would-be base stealers than pitchers such as Doug Fister or Yordano Ventura. Last season, only the valiant Gerardo Parra attempted to steal a base off Fister (who threw Parra out himself) while Ventura nearly set the record for most innings to start a career without a stolen base attempt.
To flush out what makes a pitcher good at controlling stolen base attempts, let’s compare the ten pitchers who had the lowest SBA% in 2014, with the ten highest.
Top ten qualified starters by SBA%
Bottom 10 qualified starters by SBA%
The first thing that stands out is that there are three left-handed pitchers in the top 10, while there are none in the bottom group (more on this later). Pitch velocity, shown here as average speed of their fastest pitch, accounts for only a fraction of the time required for a successful stolen base and varies greatly within each group. The lack of effect it holds on SBA% can be demonstrated by none better than R.A. Dickey whose pitches are among the slowest in the game. Age also varies widely within each group, suggesting that the skills associated with preventing stolen base attempts are not acquired through years of experience in reading big league runners.
The top ten pitchers by SBA% outperformed their FIP by a wider margin than the bottom ten pitchers in this category, which aligns with other research (again from this site) that suggested stolen base prevention helps to account for some of the gap between ERA and FIP. Interestingly, while the number of HR allowed per nine innings was the same between the groups, the ten best posted one fewer strikeout per nine innings than the ten worst. This may indicate that some strikeout potential is lost using a quicker delivery, but may also account for some the difference in between ERA and FIP between these groups.
The left-handed advantage
The top ten best pitchers at limiting stolen base attempts included three left-handed pitchers, while the bottom ten were all right-handed. So are left-handed pitchers better at keeping runners at bay? Conventional wisdom says yes. By facing the runner at first base (the station from which 86% of steal attempts originated in 2014), pitchers are better able to monitor the would-be bandit. Let’s look at the first figure again, but this time with right-handed pitchers shown in red and left-handers in blue. Other than the outliers on the far right hand side of the figure, the distribution of pitchers seem to overlap. Both right- and left-handed hurlers show a similar pattern of SBA% correlating with SB%.
When we look at average SBA% between qualified left and right-handed starters, there is only a small difference between right- and left-handers. Right-handed pitchers are more likely to have runners attempt a stolen base, but only by a margin of 0.7%, which may simply be the "Scott Feldman Effect." When runners do decide to attempt a steal, they have the same success rate against both south and north (?) paws. However, left-handers excelled at picking off runners, more than doubling their right-handed counterparts in PO% (pickoffs divided by stolen base opportunities).
Controlling the running game by handedness
|Handedness||Average SBA%||Average SB%||Average PO%|
So it appears that last season, base runners targeted starting pitchers who were less adept at controlling the running game. While the success of a stolen base did not change by handedness of the pitcher, hitters attempted to steal slightly more often against of right-handed pitchers, perhaps due to a less effective pickoff move.
. . .