Koestler pitched 68 innings at SE Losuiana while recording a 4-5 record with a 5.03 ERA, he struck out 56 hitters while walking 29. Earned All-Region and All-State honors after leading Hinds CC in 2016 with a 10-3 record and three saves while compiling a 2.95 ERA, fanning 63 batters in 55 innings pitched. Koestler was a two-sport standout and four-year letterman at Warren Central High School in baseball and football. All-State second team, All-District and All-County selection in baseball as a pitcher and infielder.