Walston (1-0) earned the win Tuesday against the Royals after allowing one unearned run while walking three and striking out two over two innings in relief.
Walston entered for the 10th with Arizona ahead 3-2 and surrendered the tying run, though it was unearned due to the automatic runner. The left-hander returned for the 11th after the Diamondbacks regained the lead and closed out the 5-3 victory with a scoreless frame. This was Walston's second appearance following Tommy John surgery, as he was activated Sept. 1.