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.

The Washington Nationals placed right-hander Trevor Williams (forearm) on the 15-day injured list (retroactive to June 1) on Tuesday with a right flexor strain and recalled left-handed pitching prospect DJ Herz from Triple-A Rochester in a corresponding move. Williams was scheduled to make the start on Tuesday against the visiting division-rival New York Mets, but that task will now fall to Herz in what will be his major-league debut. Given the nature of Williams' injury, the 32-year-old veteran will likely be out for more than two weeks. It's a tough blow for the Nats and fantasy managers, as Williams has been unexpectedly consistent so far in 2024, going 5-0 with a 2.22 ERA and 1.08 WHIP with 47 punchouts in 56 2/3 innings over his 11 starts.

The Philadelphia Phillies spent a third-round pick and $750,000 to land outfielder Jordan Viars out of high school in 2021. He doesn't have the greatest bat skills, but he gets good strength behind his swings and can hit the ball hard. FanGraphs appropriately described Viars' impact on the ball as "thump" rather than "power." Regardless of what you call it, there's reason to be excited about his seven homers and .934 OPS in 2024. He's also an above-average defender who will get a chance to play right field long-term. Viars put on a show over the course of five games last week, going 9-for-18 with four homers, 11 RBI, one walk, and five strikeouts. This one-week outburst is a small sample size, but there's at least some optimism that Viars has found his groove and can be an impact hitter in the Phillies' system.

Boston Red Sox catcher Kyle Teel was the best catching prospect in the 2023 draft and was ultimately selected No. 14 overall. He's already lived up to the hype throughout his first year of pro baseball, demonstrating impressive plate discipline, great bat-to-ball ability, decent power, and terrific skills behind the dish. Specifically, he frames pitches quite well and also has a strong arm. He has the potential to be an All-Star and could presumably give Boston the best catching tandem in baseball between himself and Connor Wong. Teel has spent all of 2024 at Double-A, but he's coming off a big week that will surely push him closer to Triple-A. Over his last six games, he went 10-for-24 with three homers, 11 RBI, three walks, and five strikeouts. He also stole two bases. There's never a "sure thing" when talking about baseball prospects, but Teel is just about as close as you'll get.

St. Louis Cardinals pitching prospect Quinn Mathews was a fourth-round pick in 2023. Although he didn't make his pro debut until this April, he's already appeared in RotoBaller's Hot Prospects to Watch series three times, which is the highest mark among any player this season. The southpaw has a low-90s fastball and rounds out his repertoire with a curveball, slider, and changeup. Of those secondary options, the changeup is the best, though all three can be effective. Mathews flashed decent control in college and has racked up strikeouts so far this year, all while keeping his walk rate relatively low. Mathews' latest outing thrust him right back into the spotlight. He struck out six batters over six shutout innings, surrendering just two hits and plunking one batter. He's been one of the most overachieving pitching prospects this season and is destined for a promotion to Double-A sooner rather than later.