Castillo allowed five runs on six hits and a walk over four innings in a no-decision Thursday against the Red Sox. He struck out five.
After holding Boston hitless through his first two innings, Castillo gave up a two-run homer to Connor Wong in the third before the Red Sox tagged him for three runs in the fourth, tying the game 5-5. It's certainly wasn't the ideal debut with Chicago for Castillo, who struggled to a 6.35 ERA across 17 innings in his final three starts with the Mariners. Through 103.2 innings this year, Castillo's ERA sits at 5.30 -- he hasn't finished a season with an ERA above 4.00 since 2018, his first full year in the majors. Castillo will look to turn things around his next time out, tentatively lined up to come at home against Reds.