As a follow-up to my little clutch hitting study, I thought it would be interesting to look at clutch pitching using the same methodology. Though I don’t believe there is good reason to expect clutch performance among hitters, I think it’s plausible that pitchers may have some clutch skill. Pitchers have to regulate their effort throughout the game and often change the way they pitch with runners on base (employing the stretch). Theses factors leave room for pitchers to perform differently when the stakes of the game change. Pitching better with runners in scoring position (RISP) may not be “clutch” in the Platonic sense of rising to the occasion, but it’s a skill worthy of examination.
I looked at individual RISP plate appearances in 1992 and estimated the impact of past clutch performance controlling for the overall pitcher performance in each area (allowed AVG, OBP, SLG, strikeout rate, walk rate, home run rate), the skill of the batter in each area, and the platoon effect (platoon = 1; 0 = otherwise). I used RISP performance in 1989–1991 to proxy clutch ability—if pitchers have clutch skill, past clutch performance should correlate with present clutch performance.
The table below lists the coefficients (reported as marginal effects) and robust z-statistics of regression estimates in seven performance areas. I used the probit method to estimate binary outcomes (outcome = 1 if an event occurred, and 0 otherwise) of individual plate appearances for hits, on-base (hits + walks + hbp), strikeouts, walks, non-intentional walks, and home runs. I used the negative binomial method to estimate the impact of the variables on the number of total bases resulting from a plate appearance.
Hit On Base TB K BB BB-IBB HR Overall 1.1801 0.8815 0.9702 0.8695 0.7657 0.6890 0.5808 [8.61] [7.20] [8.06 ] [12.34] [8.78] [8.66] [6.31] RISP -0.0239 -0.0022 -0.1192 0.0845 0.1305 0.0797 -0.0383 [0.29] [0.03] [-1.69] [1.39] [2.16] [1.43] [0.73] Batter 1.0148 1.0737 0.9816 0.9242 1.1108 0.9558 0.5831 [13.61] [17.42] [15.62] [25.56] [23.54] [22.49] [16.13] Platoon 0.0165 0.0332 0.0428 -0.0246 0.0266 0.0039 0.0071 [2.77] [5.35] [4.29 ] [5.30] [6.73] [2.79] [1.96] Obs. 21,096 23,872 21,096 23,872 23,872 23,872 23,329 Probit Probit Neg Bin Probit Probit Probit Probit
Past RISP performance is not a statistically significant predictor of 1992 RISP performance. Walk rate appears to be an exception—with pitchers consistently performing worse with runners on base (and having a z-stat > 2)—but the higher probability of walks seems to be caused by the increase in intentional walks issued with the hope of turn out a double play. When IBBs are removed, pitcher RISP walk performance loses its statistical significance.
The results do hide one thing: pitchers perform better in RISP than non-RISP situations, except when walks are involved. The table below shows the average of outcomes for all events. All differences are statistically significant.
No RISP RISP Hit 0.255 0.249 TB 0.380 0.368 BB 0.075 0.089 On Base 0.315 0.321 K 0.150 0.157 HR 0.021 0.019
The numbers remove intentional walks, therefore the worse performance in preventing walks, which also shows up for on-base probability, could represent “intentional unintentional-walks” or pitchers losing control a bit when runners are in scoring position. But if the latter were true, I would expect the numbers to be worse in the other areas. Also, because the numbers below are the percentages of all outcomes, the better numbers in RISP may also reflect better relievers entering the game for such situations.
The main story here is that the regression estimates indicate that after controlling for several relevant factors pitchers don’t appear to have any special skill over other pitchers in performing in RSIP situations. A pitcher’s overall performance level does a fine just of predicting performance, and knowing past clutch performance doesn’t appear to add useful information.