McCarthy, who suffered a skull fracture and a brain contusion, allowed one run on three hits in his two innings of work.
McCarthy struck out Billy Hamilton to start the game, and after allowing a single to Brandon Phillips, he fanned Joey Votto and Ryan Ludwick.
The D-backs gave McCarthy a lead to work with as they scored three runs in the bottom of the first off Johnny Cueto, who worked two innings in his first action since straining his right oblique in last year's National League Division Series. Cueto surrendered four runs (two earned) on five hits, walking one and striking out one.
Aaron Hill had the key hit in the inning with a double off the left-field wall that scored Adam Eaton and Martin Prado.
The Reds got on the board in the second when Eaton had trouble tracking down a Denis Phipps fly ball in center that was scored a triple. Neftali Soto drove Phipps home with a sacrifice fly.
The D-backs increased their lead to 4-1 in the second when Cliff Pennington tripled and scored on Prado's single to right.
The Reds, though, battered reliever Starling Peralta in the sixth.
Kristopher Negron tripled home a run, Votto had an RBI single, Donald Lutz drove home a pair with a double and Henry Rodriguez added an RBI single for the Reds as they took a 7-4 lead.
The Reds' Yorman Rodriguez went 2-2 with three RBIs and a home run.
D-backs up next: The D-backs' Opening Day starter, Ian Kennedy, will get the ball for the first time this spring on Thursday against a split-squad Reds team at 1:05 p.m. MT. The D-backs held Kennedy and the other three starters who have secured rotation spots out for the first week of games, so they would get six starts rather than seven. Tyler Skaggs, who is battling for the fifth spot in the rotation, will follow Kennedy to the mound.