This is great news for Red Sox fans and dynasty league managers who want to see what Mayer is capable of as a professional. Mayer was considered the top prospect available in this weekend's draft, but the slick-fielding shortstop fell to Boston at No. 4 overall. Mayer projects as a four-category fantasy contributor, though he'll take several years to reach the majors coming out of high school. Corey Seager is a great comp for Mayer's offensive skill set.