Pennington's injury will require surgery, according to D-backs manager Kirk Gibson, and the shortstop is expected to be out six to eight weeks. The Pennington news came one day after outfielder A.J. Pollock had surgery to insert pins and a plate in his fractured right hand. He, too, is expected to miss up to eight weeks.
Gregorius lost out to Chris Owings in the Spring Training battle for the starting shortstop job.
"Of course you're going to feel disappointed, but what are you going to do?" Gregorius said. "If you're going to stay bitter and be all disappointed it's going to drag you down. I just decided to look forward and try to get better. Stuff happens, nobody's perfect and you've just got to make some adjustments and go from there."
Gregorius, who was the starter at shortstop most of last season, played well for Reno, hitting .310 with 14 doubles, four triples and three home runs.
"I'm just going to look at it as the same thing I was doing down there, just another level," Gregorius said. "I'm just going to play ball and try to bring good luck to the team, just try to the best I can on and off the field. It's really awesome just to be back here."
Gibson said he has not decided yet how he will split up playing time at shortstop, but he indicated that Gregorius could see some time at second when Aaron Hill gets a day off. Gregorius played 38 games at second for Reno and 19 at short.
Steve Gilbert is a reporter for MLB.com. Read his blog, Inside the D-backs, and follow him on Twitter @SteveGilbertMLB. This story was not subject to the approval of Major League Baseball or its clubs.