Jameson Taillon left Sunday’s start against the San Francisco Giants after a left hamstring strain forced him to the trainer following an early walk to Matt Chapman. The 34‑year‑old surrendered a run in the first inning and posted a 5.19 ERA over 13 starts, leading the league with 20 home runs allowed. He was replaced by in the right‑hander Javier Assad.

Assad, 28, had just been summoned from Triple‑A Iowa after manager Craig Counsell warned he might be needed, suggesting Taillon felt discomfort before taking the mound. The Cubs’ bullpen already wrestles with injuries: Cade Horton (elbow), Matthew Boyd (knee) and Justin Steele (elbow) are all sidelined, while Edward Cabrera returned from a blister list only to take the loss in an 18-3 rout.

If Taillon lands on the injured list, Assad could slot into the rotation permanently, though Boyd is slated to return this week after two rehab outings in Iowa. The loss drops Chicago to a sub‑.500 record and intensifies pressure on a staff already scrambling for depth. The next start will test whether the Cubs can stabilize their rotation without Taillon for Chicago.