Delgado set to join six-man rotation

SAN DIEGO -- The D-backs will go to a six-man rotation for the rest of the season beginning Thursday when Randall Delgado gets the starting nod, joining Vidal Nuno, Chase Anderson, Trevor Cahill, Wade Miley and Josh Collmenter.

Going to a six-man rotation serves two purposes. First, it allows the D-backs to limit the innings for starters like Collmenter and Anderson, who have exceeded their innings totals from a year ago. It also gives the D-backs a chance to look at Delgado in a starting role.

Delgado has always had a mid-90s fastball and plus changeup, but it has been his inability to develop a consistent breaking ball to go with those two pitches that has hindered him as a starter.

The D-backs have seen some improvement with the breaking pitch, so they would like to again give Delgado a chance to start as a way of judging whether he might be a rotation candidate for 2015.

"It's a pitch he didn't have last year and really early this year," D-backs GM Kevin Towers said of Delgado's breaking ball. "It was one of the reasons we dropped him out of the rotation; he was a two-pitch pitcher. He's going to get a couple of starts in September. Hopefully he does a good job."

It's possible that the D-backs could also add another starter -- say Triple-A lefty Andrew Chafin -- and either have that starter alternate starts with Delgado each time through the rotation, or the team could shut down Anderson later this month.