The Kansas City Royals placed left-handed reliever William Smith (back) on the 15-day injured list on Monday with lower-back spasms and recalled right-hander Carlos Hernandez from Triple-A Omaha in a corresponding move. The 35-year-old veteran southpaw had been terrible of late, and this explains why. In his last five appearances out of the bullpen since Aug. 9, he surrendered 14 earned runs on 12 hits (three home runs) while walking two and striking out five over just 4 2/3 innings pitched. The brutal stretch raised his season ERA to 6.53 and his WHIP to 1.45. Smith has gone 0-4 this year for the Royals and has only picked up one save while striking out only 29 and walking 15 hitters in 41 1/3 total innings for work. He brings plenty of experience to KC's bullpen (114 career saves), but he can remain on the waiver wire in all fantasy leagues.

The Boston Red Sox selected the contract of right-hander Brad Keller from Triple-A Worcester on Monday and designated pitcher Joely Rodriguez for assignment in a corresponding move. The Red Sox recently re-signed Keller to a minor-league deal after he previously rejected an assignment to Triple-A. The 29-year-old now finds himself back in the big leagues late in the 2024 season, where he'll likely serve in a low-leverage bullpen role for the BoSox. Keller began the year pitching for the Chicago White Sox before joining Boston. In his 10 relief appearances (20 2/3 innings) for the Red Sox in 2024, he hasn't been very good, allowing 13 earned runs on 24 hits (three home runs) while striking out 17 and walking seven. Fantasy managers in all formats can continue to avoid him.

Boston Red Sox shortstop Marcelo Mayer (back), the team's top prospect per MLB Pipeline, is likely to miss the rest of the season. Mayer, 21, hasn't played since leaving a game with Double-A on July 30 and proved unable to rehab to the point of playing following his promotion to Triple-A Worcester on Aug. 13. Further medical evaluation led to a diagnosis of a lumbar strain. He has now left the WooSox to rehab in Florida, and his season is likely done, according to a major-league source. It's a disappointing end to what had been a great season for Mayer, as he hit .307/.370/.480 with eight homers, 36 extra-base hits and 13 steals while providing strong defense at short for the Sea Dogs. However, his durability is now in question, as this marks the second straight year the 2021 first-rounder has been unable to play 80 games after being shut down in August of last year with a shoulder impingement.

Miami Marlins shortstop Xavier Edwards (back) is expected to land on the 10-day injured list on Monday, according to a source, even though an MRI exam on Saturday came back negative. Edwards missed the last two games with lower-back discomfort after being pulled from Friday's contest early. The Marlins announced on Sunday that outfield prospect Griffin Conine, the son of Jeff Conine, would receive his first major-league call-up. Conine was a second-round pick out of Duke in 2018 and was acquired in 2020 as part of the Jonathan Villar trade. The 27-year-old has slashed .268/.350/.475 with 21 doubles, a triple, 19 homers and 68 RBI in 112 games at Triple-A Jacksonville this year. He will get playing time down the stretch but won't have an everyday role with Miami. It sounds like Edwards' injury isn't all that serious, so he has a good chance to return after 10 days. Vidal Brujan should play regularly at the 6 in the meantime.

The Cleveland Guardians recalled left-handed pitching prospect Joey Cantillo from Triple-A Columbus on Monday, and he's expected to appear in Game 1 of the team's doubleheader against the division-rival Kansas City Royals at Progressive Field. Right-hander Nick Sandlin is getting the starting nod on the bump, but Cantillo, the team's No. 17 prospect per MLB Pipeline, could serve in a bulk-relief role. In Cantillo's first four big-league starts, he went 0-3 with an 8.47 ERA and 1.76 WHIP while striking out 14 and waking nine in 17 innings pitched. Fantasy managers would be wise to avoid the 24-year-old southpaw in his first major-league appearance since Aug. 21, especially with a tough matchup against the Royals on tap. Cantillo is expected to be sent back to Columbus after the team's twin bill on Monday.