How Should the Appendectomy Affect Matt Holiday’s Performance? by Jeff Zimmerman April 4, 2011 Matt Holliday needed an appendectomy on April 1st. Originally it was reported that he was to be out about 4-6 weeks. Since then the time table has been moved up, even to the point that Matt has not even been place on the DL yet. I decided to go back and look historically at players that had their appendix removed, see how long they were off and did their performance change after the operation. Since 2002, 20 players have been on the DL for having having an appendectomy, 10 hitters and 10 pitchers. The average time lost was 37 days with 15 days being the shortest time (Rich Aurilia) and the longest being 134 days(Toby Borland). Borland spent so much time on the DL for the injury because he hurt his arm in rushing to return. The next longest stay was 67 days by Andy Machado in 2004. If Borland’s value is removed, the average number of days on the DL drops to 32 days. Besides finding out the number of days lost to the DL, I looked to see if the player’s performance suffered after they came back from the surgery. I decided to look at how the hitter’s OBP and SLG compared before and after the operation for the season that the operation occurred. Also, I looked at the player’s numbers the season before and after to see if there was any drop off. I compared the OBP and SLG by weighting them by the harmonic mean of the hitter’s PA. The weighted numbers were then added up and here are the results: Looking at the numbers, there are no huge differences seen in production before and after the operation. With this small sample size, having an appendix removed doesn’t seen to alter a batter’s performance. In conclusion, owners of Matt Holiday should expect him to miss around ~30 days due to the injury and his production should not suffer once he returns.