"Changes are coming Thursday for the Diamondbacks, but as to what specific roster moves will be made, General Manager Kevin Towers wouldn't get too specific.

"All I can tell you is there will be movement in a couple of areas," Towers said. "And maybe more movement later in the week. More on the position-player front. That's as far as I'll go."

The Diamondbacks are working out this afternoon at Chase Field in advance of Friday's game against the Dodgers, whom they will play to open a 10-game post-All-Star break homestand

One move could be infielder Geoff Blum, who had knee surgery in April after the Diamondbacks signed him to a two-year deal in the off-season.

Blum, who is 6 for 14 with two walks in a Triple-A Reno rehab assignment, would give the Diamondbacks options at all four infield positions.

"I talked to him in person over the break, and he said his knee is feeling good," Towers said. "We anticipated some time after the break, if not right after the break . . . so it shouldn't be too long."

As for what other move the team would make, it seems likely to involve a first baseman. The club has been dissatisfied with its production at the position and has two interesting options in the minor leagues."