He was second in the National League (NL) with a 2.10 earned run average (ERA) in 1971 for the San Diego Padres, after which he was traded to the Houston Astros, where he spent the four most productive years of his career.

Roberts was one of the best Jewish pitchers all-time in major league history through 2010, ranking fourth in career games (445; behind only Scott Schoeneweis, Ken Holtzman, and John Grabow), fourth in wins (103) and strikeouts (957) behind Sandy Koufax, Holtzman, and Steve Stone, and seventh in ERA (3.78).

[2] He played on farm clubs for the Phillies, Kansas City A's, and Pittsburgh Pirates (who claimed him on waivers in April 1964 for $8,000 ($79,000 in current dollar terms), and was chosen by San Diego with the 39th pick in the 1968 Major League Baseball expansion draft.

[6][5] Pitching for the 1963 Spartanburg Phillies he was 9-3 with a 1.79 ERA, Class-A Western Carolina League and throwing three shutouts in his 17 starts.

[2] Roberts was traded from the Padres to the Houston Astros for Derrel Thomas, Bill Greif, and Mark Schaeffer on December 3, 1971.

[2] Roberts was traded along with Bill Madlock and Lenny Randle from the Giants to the Pittsburgh Pirates for Al Holland, Ed Whitson and Fred Breining on June 28, 1979.

[2] Among Jewish pitchers all-time in major league history through 2010, Roberts ranks fourth in career appearances (445; behind only Scott Schoeneweis, Ken Holtzman, and John Grabow), fourth in wins (103) and strikeouts (957) behind Sandy Koufax, Holtzman, and Steve Stone, and seventh in ERA (3.78).

[1] After his playing career, he worked for the Allegany County, Maryland Detention Center, and served as an assistant baseball coach at Potomac State College from 1996 to 1998 in West Virginia.

[5] On January 9, 2009, Roberts died of lung cancer that he developed from asbestos exposure as a young man, at his home in Short Gap, West Virginia, at the age of 64.