Michael Kopech pitched better than his ERA indicated in 2021

After taking the mound for the first time since 2018, Chicago White Sox pitcher Michael Kopech had the type of season that could be viewed as a tale of two halves. The first half saw Kopech have an ERA of just 1.53 but that ballooned to 5.56 after the break, including a 6.43 ERA after the trade deadline.

The postseason wasn’t kind to the 25-year-old fireballer either. Although he was credited with the only win against the Astros in the divisional series, he posted an ERA of 18.00 in just three innings over two games. He allowed six runs (all earned) on just seven hits.

Playoffs aside, Kopech had a decent season, striking out 103 batters in 69.1 innings and finishing with a total ERA of 3.50. That is not too bad but according to one metric, his stats showed he actually had a better season than a traditional stat would have you believe.

Sports Info Solutions writer Corey Eiferman developed a statistic that attempts to more accurately assign responsibility to who allowed runs to score. Eiferman created Split Runs in which the bases are broken down into values of .25.

Each base a runner advances to before scoring is added together (minus any defensive errors) and assigned to the pitcher who was on the mound in the player’s at-bat.

Michael Kopech was absolutely sensational during the 2021 MLB season.

To illustrate this, Eiferman used the example of a pitcher who loads the bases and is then relieved by a pitcher who gives up a grand slam. Under current stats, the first pitcher would be charged with three earned runs while the reliever gets one.

Using the Split Runs format, the first pitcher is charged with 1.25 runs (runner scoring from third is .25, runner scoring from second is .5, and runner scoring from first is .75) while the second pitcher is credited with 2.5 runs.

With that in mind, Eiferman applied his stat to Kopech’s performance and found that he produced at a rate better than his ERA would indicate. According to his findings, Kopech produced a spRA of 2.92 compared to his 3.50 ERA.

All 27 runs Kopech allowed last season were earned and he finished with an ERA+ of 124 and a WHIP of 1.125. He closed out the 2021 season with a strikeout to walk ratio of 4.29.

What will be interesting to see is how Kopech will be used this coming season. He did most of his work out of the bullpen last year and started just four games of the 44 he appeared in. Depending on what happens to free agent Carlos Rodon and whether or not the Sox pick up a starter when free agency resumes, Kopech could find himself a part of the starting rotation.

Baseball-Reference projects Kopech will be dealing from out of the pen and will see a slight decrease in his usage from 69.1 to 63 innings pitched. Despite a decrease in innings, it projects Kopech giving up the same number of runs (27) as allowed in ’21, but will see an increase in his ERA to 3.86,

Regardless of where he’s used or the metrics by which people want to break down his performance, one thing is for sure and that is Kopech will play a key role in the success of the White Sox in their drive toward a title.