Just saw this on the dallas morning news blog by anthony andro:
The Texas Rangers left-hander has been diagnosed with Thoracic Outlet Syndrome, and will miss the remainder of the season. Harrison is weighing his options regarding surgery, but will not not pitch again this year. If he has surgery, it could come as early as Monday. Harrison experienced some discomfort during a rehab outing Wednesday in Frisco. The left-hander is 4-5 with a 6.11 ERA.
Can't say I'm completely surprised and sucks for him, curious if he'll be starting next year in AAA or maybe even as our long man