A hard thrower but often wild, Estrada was one of the brightest of several young Orioles pitchers who arrived in the ML about the same time. His 18 wins as a rookie topped the AL in 1960. He won 15 the next season but led only in walks. His 17 losses were the most in the AL in 1962. He never recovered from an elbow injury in 1963. After his retirement he found frequent employment as a pitching coach.