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.