MASH Report: Predicting Pitcher Injuries

A few years back I created a metric to help find pitchers who are showing signs of a possible injury. I named the metric PAIN (Pitcher Abuse INdex). While I can easily publish the information at all times, I have not been able to dive into the results  as often as I would like. With the new arrangement with BJ Maack and me with the MASH Report, he will be looking at more of the daily and rehab updates and I can then dive into some deeper topics. Today, I will give an update on possible pitcher injuries.

There are just two inputs into the PAIN metric, fastball velocity, and Zone%. I have found drops in both to be indicators of possible pitcher injuries, so I decided to include the pair in the metric. Initially, I had to do a little back fitting to get the system to work. I have made a few minor tweaks over the years, but it has remained relatively constant.

One of the more recent tweaks I have made is to lower the bar for the players at risk. Initially, I made 100 the threshold for risk, but looking back, values of 90 are injured quite often. At some point in the future, I may adjust the formula so 100 is the threshold again.

For reference, here are the overall ranks for every pitcher comparing their 2015 values to their 2016 values.

While everyone is listed, let me narrow down the list to some regulars. Here are the pitchers with a PAIN value higher than 90 and has thrown a minimum of 1000 pitches in each of 2015 and 2016.

Going over the list, here are teach pitcher’s 2016 injuries and production.

• Felix Hernandez: On the DL with a calf strain.
• Patrick Corbin: Hasn’t missed a start, but every one of his stats trending the wrong direction from 2015. I could see him hiding an injury.
• Mat Latos: Pitched so ineffectively for the White Sox, he was released.
• Marco Estrada: On the DL twice for back issues.
• Andrew Cashner: On DL twice. Once for hamstring and the other time for a strained neck.
• Cole Hamels: Dealt with a groin issue in late April, but otherwise a productive season. His high PAIN is all based on his drop in Zone% from 47% to 42%. With the drop in Zone%, his walk rate and gone from 2.6 BB/9 to 3.4 BB/9. He probably had a better season overall in 2015, except in 2016 he has been able to strand quite a few runners and keep his ERA under 3.00. Hamels looks to be an exception in PAIN this year.
• Jake Peavy: I am not sure if Peavy is injured or just aging quickly. Either way, he has not been productive this season and may soon be out of the league.
• Madison Bumgarner: The 26-year-old has been able to keep his production up even with a 1 mph drop in velocity, higher home run rate, and a higher walk rate. Like Peavy, I wonder if the small declines are from aging or an injury.
• Drew Pomeranz: Pomeranz has been decent this year, but after being traded to Boston, people wonder if he is hurt. His ERA with Boston is at 5.26 and his walk rate is up at 4.6 BB/9.
• Michael Wacha: On the DL with an inflamed shoulder.
• Lance McCullers: On the DL twice. Once for a sore shoulder and also a sore elbow.

Of the 12, five have been on the DL, four others have been completely ineffective, one with mixed results, and two good pitchers. I wish the finder worked a little better for these guys, but there was selection bias in effect because an injured starter will have problems reaching 1000 pitches.

Besides looking at the top of the list, the bottom of the list can be full of pitchers on the comeback. Here are the pitchers with a PAIN score less than -90 and have thrown 1000 pitches in 2015 and 2016.

The list has a couple pitchers who have seen their velocity increase because of moves to the bullpen like David Phelps. Generally, the table is full of this year’s surprises like Matt Moore, James Paxton, and Danny Duffy.

Since we are about three-quarters of the way into the season, the season-to-season comparisons no longer work at finding pitchers on the quick decline. Here is the full PAIN ranking using March to June values and values from July and August.

The one item to be careful with this list is the possible drop in Zone% from just a few starts, but no sign of a velocity drop. Here are my thoughts on some regulars who are seeing a velocity drop to go with the Zone% decline.

• Adam Wainwright: From now until he retires, I expect the 34-year-old Wainwright to be overvalued and some of his in-season decline is more age than injury based. People will hope for the 2009 to 2013 Wainwright, but he is no longer that good.
• Archie Bradley: Until his last start, Bradley’s velocity had been on a steady decline.

With the decline, his K/9 has dropped from 9.3 to 7.6 and his BB/9 and jumped from 4.2 to 5.5 from the season’s first half to the second half. There definitely could be an injury lurking with him.

I am done for today looking at possible pitcher injuries. As always, let me know if you have any suggestions or ways to improve the process.