Gray, who was making his second start of the spring, struggled with his command, walking four while allowing seven runs on five hits over two innings.
The A's got back into the game in the second off Shelby Miller, as they scored three runs thanks in part to RBIs from Marcus Semien and Jake Smolinski. Oakland tacked on another three runs in the third as Semien doubled home a pair of runs.
Semien finished up 3-for-3 with four RBIs.
Miller, who had pitched well in his first two outings of the spring, allowed six runs on five hits over 2 2/3 innings.