Arizona Diamondbacks rookie left-hander Blake Walston will receive the start on Tuesday against the visiting division-rival San Francisco Giants. This will be Walston's third MLB appearance and just his second major-league start after making his big-league debut on May 1 against the Los Angeles Dodgers. In his first start on May 26 against the Miami Marlins, he tossed 4 2/3 scoreless frames with one walk and four strikeouts to pick up a no-decision. The 22-year-old southpaw could see another start after this one if he fares well again, as the D-backs currently have Zac Gallen (hamstring), Merrill Kelly (shoulder) and Eduardo Rodriguez (shoulder) all on the injured list. Walston is the club's No. 25 prospect, per MLB Pipeline, and will have a pretty middling matchup against the Gigantes in his second career start.

Arizona Diamondbacks starting pitcher Blake Walston made his MLB debut against the Miami Marlins on Sunday. The 22-year-old allowed only four hits over 4 2/3 shutout innings in the loss to Miami. The southpaw struck out four batters while allowing only one walk in the contest. It's uncertain if this was a spot start or if Walston is going to stick around in the D-Backs rotation. If he stays, Walston's next outing would be versus the New York Mets. He could have some deep league streaming appeal for that game.

The Arizona Diamondbacks have sent pitcher Blake Walston back down to Triple-A Reno. Walston made his debut on Monday versus the Los Angeles Dodgers. Walston went 3 2/3 out of the bullpen for the Diamondbacks and was wild with four walks and two runs allowed. Walston's trip was brief, but it is likely that he will be back with the Diamondbacks when they need more pitching depth or an injury occurs. Replacing Walston on the active roster will be pitcher Matt Bowman. Bowman was acquired from the Minnesota Twins for cash considerations on Thursday. Both Walston and Bowman can remain on the waiver wire in all formats.

The Arizona Diamondbacks have called up 2019 first-round draft pick Blake Walston. The left-handed pitcher is expected to provide depth to the bullpen, which he was able to do in Wednesday's 8-0 loss to the Dodgers. The 22-year-old's debut was a mixed bag, tossing three-and-two-thirds in relief of starter Jordan Montgomery. He walked four batters but was able to strike out five Dodgers as well, giving up three hits and two earned runs during the outing. He's off the radar for season-long fantasy, but if he were able to earn a spot start (he's worked predominantly as a starter in the minors) he could be a potential DFS option depending on the matchup.