3. Corey Kluber
Speaking of former Cleveland pitchers who were traded for integral parts of their current roster, Corey Kluber.
After being dealt to the Texas Rangers in exchange for Emmanuel Clase ahead of the 2020 season, Kluber has seen mixed results on the mound. From missing all but one inning of his first season in Texas to being a solid option for the Yankees and Rays the following two years, and finally, his year in Boston, which did not go well.
The former two-time Cy Young Award-winning pitcher is currently at the point in his career where he bounces around from organization to organization, with there being some level of hope of winning a World Series. Even though Cleveland is an organization that should be better next season and is closer to making that possibility a reality, they are not yet at the level of teams that players sign in an attempt to win a championship. The Guardians are going to need at least two more offseasons in order to reach that level. With Kluber turning 38 early next season, there is a good chance his playing days are behind him by the time Cleveland is in a position to be a genuine contender.