As fantasy baseball strategies shift in Week 10, key decisions emerge regarding new promotions and returning closers. Marcelo Mayer of the Boston Red Sox, a highly touted prospect, has joined the majors but faces skepticism about his fantasy impact due to concerns about his power potential and batting average. Meanwhile, Alejandro Osuna of the Texas Rangers shows promise with his recent promotion but may struggle with playing time and efficiency on the base paths. Lastly, Camilo Doval has been reinstated as the closer for the San Francisco Giants, though a decline in his performance metrics raises questions about his sustainability in that role.

Marcelo Mayer, the Boston Red Sox's highly touted prospect, has made his MLB debut, showcasing promising talent in his first few games. The 22-year-old, ranked No. 8 on MLB's top prospects list, demonstrated his capability with notable hits and an impressive OPS. However, his groundball tendencies and struggles with non-fastball pitches may challenge his consistency against major league pitchers.

Denzel Clarke debuted with the Oakland Athletics but faced early struggles, managing only one hit in 19 at-bats. Known for his size and speed, Clarke's high strikeout rate poses concerns, highlighting the need for adjustment at the major league level. Meanwhile, Robert Hassell III of the Washington Nationals has shown flashes of potential since his promotion, including a three-hit game and his first home run. With a solid batting average in Triple-A prior to his call-up, he could be a key player as the Nationals rebuild post-Juan Soto trade.

As the fantasy baseball season progresses into Week 10, key prospects are making noise, particularly with recent MLB call-ups. The Boston Red Sox have promoted top prospect Marcelo Mayer, leading to discussions about other hitters ready for the majors. Roman Anthony, also from the Red Sox, boasts impressive Triple-A stats with a high WRC+ and power potential, but awaits his opportunity. Meanwhile, Kansas City's Jac Caglianone is dominating Triple-A and could soon make an impact with the Royals. Colorado's Ryan Ritter is showing significant improvement and could push for a call-up as the Rockies' offense struggles.

Shay Whitcomb of the Astros continues to produce power, and if he gets a consistent spot in Houston's lineup, he could become a valuable fantasy asset. Finally, the Nationals' Brady House is experiencing a resurgence, making him a name to watch closely.

The mid-week waiver wire rankings for MLB Week 9 highlight key players to consider for your fantasy baseball roster. Notably, Marcelo Mayer, the Boston Red Sox top prospect, is highlighted for his potential impact as he solidifies his place among fantasy managers. Daniel Palencia has emerged as the Chicago Cubs closer, boasting four saves without allowing a run in four appearances. Meanwhile, Kansas City Royals' Jac Caglianone continues to impress at Triple-A, making a case for promotion with a .343 batting average and 10 RBIs. Other noteworthy mentions include Bubba Chandler and Cam Smith, who also show promise as strategic adds.

As the fantasy baseball season ramps up, three standout prospects are positioned to make a significant impact. Jacob Misiorowski, Andrew Painter, and Marcelo Mayer are exciting names to consider for your roster.

Misiorowski, a right-handed pitcher for the Milwaukee Brewers, has been dominating Triple-A with a 1.60 ERA and 71 strikeouts in just over 56 innings. His high strikeout rate suggests he could be a game-changer once he gets called up, likely following some rotations adjustments from the Brewers.

Andrew Painter, the elite pitching prospect of the Philadelphia Phillies, is also on the cusp of making his MLB debut. After recovering from Tommy John surgery, Painter has posted a 3.09 ERA in Triple-A, showcasing his potential. He’s expected to be called up in July, making him a valuable stash for fantasy leagues.

Finally, Marcelo Mayer of the Boston Red Sox is a promising infielder who’s already making waves in the majors after a strong start in Triple-A, demonstrating impressive power and contact skills. He could be a key contributor in various infield positions for the Red Sox, especially with current injuries in the team.