An outstanding defensive catcher, Wynegar was TSN AL Rookie of the Year in 1976 and represented the Twins at the All-Star Game his first two seasons, becoming the youngest player (to that point) to appear in the mid-summer game in 1976. A slow-footed switch-hitter, he had initial success after being traded to the Yankees, batting .295 for them in 1982-83 and catching Dave Righetti‘s 1983 no hitter. He became a full-time starter in 1984. After an injury-riddled 1985, Wynegar succumbed to the high-pressure atmosphere and suffered from physical and mental fatigue in 1986. Various foot problems in 1987 caused more trouble.
Wynegar won the Appalachian League batting title (.346) in his first pro season (1974).