Diamondbacks' Blake Walston: Needs Tommy John surgery

Diamondbacks manager Torey Lovullo said Friday that Walston will undergo Tommy John surgery, Alex Weiner of ArizonaSports.com reports.

It's not clear when Walston was injured, but he missed time last season while at Triple-A Reno with an elbow issue. Because he's a starter and it's a full UCL repair, the left-hander will probably be sidelined until around midseason of next year.