He played in Major League Baseball (MLB) for the Los Angeles Dodgers (1978–87) and Oakland Athletics (1988–94).

[1] He helped lead the Hurons, coached by Ron Oestrike, to the 1976 College World Series, losing to Arizona in the Championship Game.

[2] Welch gained national fame with the Dodgers during their 1978 season, when as a 21-year-old rookie he struck out Reggie Jackson of the New York Yankees with two men on base and two out in the top of the ninth inning of Game 2 of the 1978 World Series.

The only Atlanta base runner was Larvell Blanks, who singled in the fourth inning and was retired on a double play.

In an odd twist of fate, however, Welch did not throw a single pitch against the San Francisco Giants during the World Series itself.

In 1981, Welch and The New York Times sports columnist George Vecsey co-wrote Five O'Clock Comes Early: A Cy Young Award-Winner Recounts His Greatest Victory, which chronicled Welch's battle with alcoholism that he said started at the age of sixteen: "I would get a buzz on and I would stop being afraid of girls.

[6] His son Riley Welch was a 34th round selection by the Oakland A's in the 2008 MLB draft out of Desert Mountain high school in Scottsdale, Arizona but did not sign and went on to play college baseball at the University of Hawaii.

[8] Welch died of a broken neck resulting from an accidental fall in the bathroom of his Seal Beach, California, home on June 9, 2014, at the age of 57.