Red Sox manager Alex Cora said Monday that Casas was seeing a doctor, and they were looking at an MRI. But even before knowing those results, Cora said it was unlikely the first baseman would get back in the lineup.
Casas was placed on the 10-day injured list Saturday. Boston, last in the AL East, had only 11 games remaining after the series opener at Texas on Monday night.
"To ramp up again ... it doesn't make any sense. That's where we're at," Cora said. "For this season, it doesn't make sense to get him back here."
Casas hit .263 with 24 home runs and 65 RBIs in 132 games. He ranked first among AL rookies in walks and second in homers. He batted .317 with 15 home runs in 54 games after the All-Star break.