MLB: Jeff Zimmerman on When to Drop Struggling Pitchers

MLB: Jeff Zimmerman on When to Drop Struggling Pitchers

A couple weeks ago, I looked into when to give up on hitters who struggle to start the season.  (i.e. two months). It's now time to find the time to ditch pitchers who are struggling early in the season. In the end, walk and home-run rates are all that's needed with just a month's sample. 

In 2021 drafts, both Lucas Giolito and Luis Castillo were early-round draft picks who struggled out of the gate. In April, Giolito had a 5.68 ERA while Steamer projections placed him as a 4.00 ERA guy. As for Castillo, he had a 6.28 ERA and 1.60 WHIP with an ERA projected to be around 3.50. Both pulled it together with Castillo having a 3.90 ERA in the second half and Giolito a 3.50 ERA over the same time frame. 

On the other hand, Kyle Hendricks and Sonny Gray never did rebound from their early struggles. My goal was to find any indicators that pointed to the pitchers who have lost some talent compared to those who may have been unlucky. 

To start the analysis, I took all the pitchers since 2010 who had their ERA a full run (1.00) above their preseason Steamer projection. Then, I compared how these pitchers performed over the rest of the season, looking for any common traits for those who struggled and those who regressed back to their projection.

After cutting and dicing the data several ways, two common traits stood out: a jump in walk and home-run rates.

A couple weeks ago, I looked into when to give up on hitters who struggle to start the season.  (i.e. two months). It's now time to find the time to ditch pitchers who are struggling early in the season. In the end, walk and home-run rates are all that's needed with just a month's sample. 

In 2021 drafts, both Lucas Giolito and Luis Castillo were early-round draft picks who struggled out of the gate. In April, Giolito had a 5.68 ERA while Steamer projections placed him as a 4.00 ERA guy. As for Castillo, he had a 6.28 ERA and 1.60 WHIP with an ERA projected to be around 3.50. Both pulled it together with Castillo having a 3.90 ERA in the second half and Giolito a 3.50 ERA over the same time frame. 

On the other hand, Kyle Hendricks and Sonny Gray never did rebound from their early struggles. My goal was to find any indicators that pointed to the pitchers who have lost some talent compared to those who may have been unlucky. 

To start the analysis, I took all the pitchers since 2010 who had their ERA a full run (1.00) above their preseason Steamer projection. Then, I compared how these pitchers performed over the rest of the season, looking for any common traits for those who struggled and those who regressed back to their projection.

After cutting and dicing the data several ways, two common traits stood out: a jump in walk and home-run rates. Before it started, I figured BABIP would be the driver, but it was constant for those who continued to struggle and those who pulled it together. 

For walks, a one-month jump of 1.0 BB/9 over their projection pointed to a pitcher who would continue to struggle. For home runs, it was a jump of 0.75 HR/9. When a pitcher pushed both over the line, they had little chance of rebounding. 

The preceding benchmarks aren't the perfect calculated dividers, but they are easily remembered. I wish the home-run benchmark was 0.5 or 1.0, but both were too small or big. Also, if there is one of the pair to believe, it's the walks. 

For example, here are the pitchers from 2021 who saw their March/April ERA jump by more than a run over their projection. I grouped them into four groups comparing their projections versus early performance.

Group

  1. BB/9 increased by >= 1.0 and HR/9 increased by >= 0.75
  2. Just BB/9 increased by >= 1
  3. Just HR/9 increased by >= 0.75
  4. Neither BB/9 increased by >= 1.0 and HR/9 increased by >= 0.75
 Steamer  March/April  Second Half  March-Steamer  Second Half - Steamer  
NameERABB/9HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9
Kyle Hendricks4.2221.37.543.246.162.81.33.331.162.71.940.80
Patrick Corbin4.012.91.210.475.53.36.323.32.26.462.572.12.30.41
Tarik Skubal4.373.51.56.145.73.34.31.32.41.772.181.8-0.07-2.20.9
Taylor Hearn4.294.31.56.946.93.14.52.81.22.652.691.60.21-1.5-0.3
Matt Moore4.953.31.79.827.43.36.974.61.74.874.051.62.011.30
Vince Velasquez4.263.31.66.5782.99.413.73.32.34.71.45.140.41.7
Chad Kuhl4.843.91.46.329.22.34.974.31.91.485.30.90.120.50.5
Max Fried3.813.3111.454.12.51.741.50.67.650.781.5-2.07-1.8-0.4
Sonny Gray3.993.71.15.935.325.033.31.41.941.590.81.04-0.40.2
Average =         3.62.781.61.18-0.30.4
                
NameERABB/9`HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9
Tyler Matzek3.493.91.14.916.51.61.784.20.31.412.670.6-1.710.3-0.8
Mitch Keller4.453.91.38.26.31.45.43.40.53.752.360.20.95-0.5-0.8
Zach Davies4.983.11.49.477.11.48.134.42.64.494.0503.151.31.2
Brad Keller4.743.61.195.513.963.71.24.261.87-0.1-0.780.10.1
Jose Quintana4.442.91.510.138.81.44.942.71.95.695.89-0.20.51-0.20.4
Austin Gomber5.3241.56.657.40.86.324.42.71.333.4-0.810.31.1
Average =         3.493.3700.520.20.2
                
NameERABB/9`HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9
Drew Smyly4.163.51.48.053.34.34.472.423.9-0.182.90.31-1.10.6
Logan Allen4.7141.49.19443.9214.480.042.6-0.81-2-0.4
Richard Bleier3.742.60.86.3503.22.961.502.61-2.592.4-0.78-1.1-0.8
Liam Hendriks3.292.61.24.350.93.52.270.91.11.07-1.782.3-1.01-1.8-0.1
Trevor Stephan4.563.51.65.914.23.44.453.91.81.350.71.8-0.10.30.2
Bryse Wilson4.393.21.36.753.835.3631.62.360.571.70.97-0.20.3
Anthony Bass3.883.416.972.62.62.772.81.43.08-0.821.6-1.12-0.70.4
Kenta Maeda4.2831.46.171.92.74.662.11.21.89-1.051.30.37-0.9-0.2
Jorge Lopez5.053.41.67.483.72.56.324.41.72.420.360.91.2710.1
Frankie Montas4.213.11.36.22.62.22.1730.61.99-0.550.9-2.04-0.1-0.7
Jordan Lyles5.473.51.86.752.32.65.492.82.31.28-1.210.90.01-0.70.5
Luis Castillo3.563.21.16.292.61.83.183.212.73-0.640.8-0.380-0.1
Chris Stratton4.183.41.36.081.424.684.11.41.89-2.030.80.50.80.1
Average =         2.39-0.71.6-0.22-0.50
                
NameERABB/9`HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9ERABB/9HR/9
Ryan Tepera4.241.15.44.51.81.962.70.41.20.480.7-2.24-1.3-0.7
Rich Hill4.513.71.47.252.824.012.80.92.74-0.830.6-0.5-0.8-0.5
Jameson Taillon4.632.61.56.2312.13.52.91.21.6-1.590.6-1.130.3-0.4
Jesus Luzardo3.8531.35.43.61.86.4451.41.550.560.52.5820.2
Lucas Giolito4.043.31.45.683.61.82.652.31.11.650.20.4-1.39-1.1-0.3
Connor Brogdon4.183.71.46.33.61.82.312.30.82.12-0.10.4-1.87-1.4-0.7
Merrill Kelly4.682.91.46.332.31.34.412.61.11.66-0.55-0.1-0.27-0.3-0.3
Zach Plesac4.742.61.75.8111.44.952.51.41.07-1.6-0.30.21-0.2-0.3
Chris Paddack3.862.31.35.42.70.84.311.10.91.540.4-0.50.44-1.2-0.4
Alex Cobb4.662.61.57.162.80.62.6340.72.50.13-0.9-2.031.3-0.8
Average =         1.76-0.290.1-0.62-0.3-0.4

From the group who had both their walk and home-run rate up, only two (Skubal and Kuhl) met their projections. Max Fried bucked the trend by performing great in the second half, but he needed an IL stint to get right. Even though they were highly regarded, Patrick Corbin, Kyle Hendricks and Sonny Gray continued to struggle. 

As for Giolito and Castillo, Giolito was firmly in the safe group. As a group, they outperformed their projections. The only miss in the last group was Jesus Luzardo, who never did put it all together. As for Castillo, he just barely missed the last grouping with a 0.8 HR/9 jump. 

It's just that simple and simple can be great at times. So when to consider dropping pitchers and hitters have been answered. Next on the offseason to-do list are examining relievers who transitioned to starter and the pitchers who returned from Tommy John surgery.

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ABOUT THE AUTHOR
Jeff Zimmerman
Jeff is a former RotoWire contributor. He wrote analytics-focused baseball and football articles for RotoWire. He is a three-time FSWA award winner, including the Football Writer of the Year and Best Football Print Article awards in 2016. The 2017 Tout Wars Mixed Auction champion and 2016 Tout Wars Head-to-Head champ, Zimmerman also contributes to FanGraphs.com, BaseballHQ and Baseball America.
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