Hill was initially hit on the left hand by a James McDonald pitch last Tuesday. Initial X-rays, as well as a second set taken later in the week, showed no break, and he sat out until pinch-hitting -- and hitting a double -- on Saturday against the Dodgers.
D-backs manager Kirk Gibson said that Hill told him on Sunday that the hand felt better and that he could play, but when Hill checked his swing in his first at-bat of that game, he felt a sharp pain.
An MRI exam was taken at that point, again revealing no problems, but a CT scan ultimately revealed the break.
"It doesn't require surgery; it should heal up nicely," Gibson said. "We hate to lose him."
Gregorius was acquired by the D-backs in a three-team trade that sent former top prospect Trevor Bauer to Cleveland. Gregorius felt pain in his throwing elbow a couple of weeks after the December trade, and the team shut him down from throwing.
The D-backs were extremely cautious with Gregorius and did not allow him to start throwing until March 2; he did not start throwing across the diamond when fielding ground balls until later in the month. Gregorius played nine innings for Triple-A Reno on Monday, the first time he had played in the field all season. Prior to that, he had served only as the designated hitter.
"He's been throwing a ton," Gibson said. "He's probably got 100 at-bats, including Spring Training. He's ready."
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.