Bruce Chen 'significantly better' Monday

Royals pitcher Bruce Chen threw 25 pitches in a simulated game Monday and reported no issues with his back, MLB.com reports.

"It felt good," Chen said. "Really good. The last three days, it really got better, significantly better."

Chen threw all of his pitches during the session; however, he has no timetable to begin a rehab assignment. He has been out since April 25 while recovering from his back injury.