The Houston Astros added left-hander Brandon Walter to their taxi squad, and The Athletic's Chandler Rome suggests he could make the start on Tuesday against the Tampa Bay Rays, a team that hasn't been good against lefties in 2025. Houston currently has not listed a starter for Tuesday's game. Walter has looked good at Triple-A Sugar Land this year, going 2-1 with a 2.27 ERA and 0.70 WHIP with 34 strikeouts and seven walks in 35 2/3 innings over nine appearances (five starts). The 28-year-old southpaw had a cup of coffee with the Boston Red Sox in 2024 in his big-league debut and allowed 17 runs (16 earned) while walking seven and striking out 16 in 23 relief innings. This would be Walter's first-ever MLB start if he gets the nod on Tuesday, and while the matchup is a good one, Walker would be a shaky deep-league streaming option in fantasy.

The Philadelphia Phillies optioned right-handed pitching prospect Mick Abel to Triple-A Lehigh Valley on Monday and recalled right-hander Max Lazar in a corresponding move, according to The Philadelphia Inquirer's Lochlahn March. Abel will head back to the farm despite the fact that he looked excellent in his spot start on Sunday against the Pittsburgh Pirates. The 23-year-old threw six shutout innings with five hits allowed, no walks and nine strikeouts to pick up the victory in his major-league debut. After the strong start, the team's No. 9-ranked prospect per MLB Pipeline, will surely be considered for another major-league call-up later this year if the Phillies need another arm. For now, though, veteran right-hander Taijuan Walker will take over the rotation spot of Aaron Nola (ankle), who was recently placed on the 15-day injured list. Lazar has a 3.12 ERA in 15 relief outings for Lehigh Valley this year.

The Chicago White Sox announced on Monday that they reinstated outfielder Austin Slater (knee) from the 10-day injured list and optioned infielder/outfielder Brooks Baldwin to Triple-A Charlotte in a corresponding move. Slater will make the start in left field and will hit seventh right away in Monday's series opener against the visiting Seattle Mariners and right-hander Luis Castillo. The 32-year-old veteran could play regularly in Chicago's outfield with both Andrew Benintendi (calf) and Mike Tauchman (hamstring) still on the IL, but eventually, he could be on the short side of a platoon in left field against left-handed pitching. Slater had played in only eight games this year before needing surgery to fix a torn meniscus in his right knee and had gone 5-for-20 with a homer and two doubles. He's worth a waiver-wire pickup in AL-only formats.

Minnesota Twins infielder/outfielder Willi Castro (knee) is starting at second base and is batting ninth in Monday's series opener against the division-rival Cleveland Guardians at Target Field. A right-knee contusion kept Castro out of the lineup for the Twins the last two games, but he's back in there now to face a pitcher in left-hander Logan Allen that he's hit .222 against with a .444 OPS in nine career at-bats. The 28-year-old was a league-average hitter in 2024 and has hit .250 (8-for-32) with a home run, one steal and eight runs scored in 10 games since he returned from the 10-day injured list on May 5 from a hamstring injury. The 28-year-old Puerto Rican switch-hitter has slashed .235/.306/.367 on the year with only two homers, six RBI, 15 runs and two steals in 98 at-bats. Castro won't be a recommended DFS target on Monday in the nine-hole.

Chicago Cubs manager Craig Counsell said that left-hander Shota Imanaga's (hamstring) return will be "well into June." The skipper also said on Monday that Imanaga will begin throwing off a mound towards the end of next week. Imanaga is currently on the 15-day injured list with a strained left hamstring and won't be returning anytime soon. It means that right-handed pitching prospect Cade Horton should stick around a while longer in Chicago as either a traditional starter or bulk reliever. Even though Imanaga's return isn't just right around the corner, the 31-year-old Japanese southpaw should remain stashed in all fantasy leagues as Chicago's ace when he's healthy. Before getting hurt, he had gone 3-2 with a nice 2.82 ERA and 1.09 WHIP with 34 strikeouts and 14 walks in 44 2/3 innings over his first eight starts. Imanaga was an All-Star in his debut season in MLB in 2024.