Keller appeared out of the bullpen for the first time in his MLB career on Wednesday Mitch Keller has been regarded as one of the Pittsburgh Pirates’ best pitching prospects since being drafted in the second round of the 2014 MLB Draft. Keller was lights out during his Minor League career including ERA’s of 2.35, 3.03, and 3.48 in 2016, 2017, and 2018, respectively. The Cedar Rapids, Iowa native made at least 23 starts in all three seasons. This strong stretch of quality outings led into Keller’s Major League debut on May 27, 2019 against the Cincinnati Reds. He allowed…