He began working with the Atlanta Braves' organization in 1979 and is currently employed as the Baltimore Orioles' pitching coach.
Although Leo Mazzone was born in West Virginia, his family lived on the other side of the Potomac River's north branch in Westernport, Maryland. Growing up there, one of his friends was Sam Perlozzo of nearby Cumberland. Mazzone was even the best man at Perlozzo's wedding. Later, as manager of the Orioles, Perlozzo would help convince Mazzone to leave his longtime position as Atlanta pitching coach and come to Baltimore.
Mazzone has earned a reputation as one of the best pitching coaches in the modern era, having developed and coached perennial all-star pitchers such as Greg Maddux, Tom Glavine, and John Smoltz. Over the years, pitchers who have joined the Atlanta Braves under Mazzone have often undergone marked improvement over previous years with other organizations, and show a marked decrease in performance upon moving to other systems with Denny Neagle, Mike Hampton, and Jaret Wright being notable examples.
Mazzone's "accidental trademark" is his rocking back and forth while sitting in the dugout. On television broadcasts of Braves games, the camera would often show him rocking back and forth during the games, stopping only when his pitchers began to have difficulties.
Mazzone's pitching philosophies state that pitchers should throw more between starts (two sessions instead of one), utilize the outside corner of the strike zone and utilize a fastball to set up breaking balls.