after retirement, wagner served the pirates as a coach for 39 years, most notably as a hitting instructor from to . arky vaughan, ralph kiner, pie traynor (player-manager from –), and hank greenberg (although greenberg was in his final major league season in 1947, his only season with the pirates, and very well established) all future hall of famers, were notable "pupils" of wagner. during this time, he wore uniform number 14, but later changed it to his more famous 33, which was later the number retired for him. (his entire playing career was in the days before uniform numbers were worn.) his appearances at national league stadiums during his coaching years were always well received and wagner remained a beloved ambassador of baseball. wagner also coached baseball and basketball at carnegie institute of technology, which is now part of carnegie mellon university.