Tolleson blew out his back in mid-April and underwent disk surgery, but he has already been throwing bullpen sessions and expects to begin a Minor League rehab assignment before the month is out.
"It feels really good, no pain at all," Tolleson said. "I'm still building back my arm strength, but it feels good and I'm running again. I start [pitcher fielding practice] this week and I think being back in early August is very doable."
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.