Kyle Schwarber
After being named an All-Star for his first-half performances with the Washington Nationals, the Red Sox traded Aldo Ramirez to Washington to acquire the power-hitting lefty's services. It's safe to say he did not disappoint in his short stint in Boston.
In only 41 regular season games for the Red Sox, Schwarber quickly became not only a fan favorite — dubbed "Kyle from Waltham" — but also an integral piece in the Red Sox lineup. He posted a .291/.435/.522 triple slash line and a .957 OPS. However, his most significant achievement with the Sox was his postseason performance. He hit three home runs, including a grand slam that rocked Fenway Park, during Boston's 2021 run to the ALCS.
After J.D Martinez opted into the final year of his $110 million deal the Red Sox chose not to re-sign Schwarber, letting him walk in free agency after one season.