Mitch Keller is currently the Pittsburgh Pirates best prospect. He currently ranks 26th in the entire minors, and for a good reason. Now, he is set to graduate from prospect status in 2020.
Last season in Triple-A, Keller pitched to the tune of a 3.56 ERA, 3.60 FIP, and 1.24 WHIP. He walked just 3.0 batters per 9, while striking them out at a 10.7 rate. His ERA ranked 4th in the International League, while he led the league in K/BB%. His HR/9 of 0.79 also led all Triple-A pitchers with at least 100 innings under their belt during 2019.