CHICAGO — With the trade deadline two weeks away, all eyes will be on pitching. The Chicago Cubs have made it clear that’s their focus, and Monday only highlighted the issue.In the 10th inning of the team’s 8-6 loss to the Detroit Tigers, Cubs reliever Trent Thornton took a 108.9 mph grounder off his left foot and quickly exited the game, limping off the field with the help of a trainer and his manager.“Trent’s got a left heel contusion,” manager Craig Counsell said. “The X-rays were negative. I guess the heel’s a little tricky on X-rays, so we’ll have to see how he’s doing tomorrow. He’s limping pretty badly right now.”Thornton signed a minor-league deal with the team in the offseason and was working his way back from a left Achilles tear. Counsell said the Achilles is not a concern at the moment for the veteran righty, who has been huge for a bullpen battered by injuries. Thornton entered the night with a 2.40 ERA in 30 innings and has been working high-leverage moments for a little while now.“That was a tough one,” Ian Happ, who hit a game-tying home run in the eighth inning, said. “Seems like he’s doing all right. But it was loud, even in left field. Ball was hit really hard. He’s a competitor. He wants to be out there. He wants to pitch. He’ll be back soon.”