Hubbard struggled to adjust in the American Football League (AFL), and was cut by both the Raiders and the Denver Broncos in preseason.

[4] Hubbard was selected in the eleventh round by the Oakland Raiders in the 1968 common draft, but was released in preseason cuts due to an initial inability to adjust to the professional game.

He met the same fate with the Denver Broncos, before signing with the Hartford Knights of the Atlantic Coast Football League (ACFL).

Despite not being the team's full-time running back, he still led the league in rushing yards, just ahead of his tandem partner, journeyman Mel Meeks.

After Hubbard's success with the Knights, the Raiders exercised a reserve clause in his previous contract and signed him to their active roster.

[6] His career yards per carry average was higher than many of the games legendary running backs, including Walter Payton, O. J. Simpson, Eric Dickerson, Emmitt Smith and Marshall Faulk.

Hubbard was a standout for the Raiders from 1971 to 1974 and part of 1975, and gave Oakland's fearsome air attack a balanced running threat.

Hubbard scored 24 touchdowns (23 rushing, 1 passing) during his career, six of which were against his favorite opponent, the formidable Kansas City Chiefs.

[8] Hubbard was featured on the cover of Sports Illustrated on December 17, 1973, after the Raiders won a pivotal game over the division rival Chiefs.

[10] Marv was a country musician and songwriter for a brief period after football, and released the single "Fullbacks Ain't Supposed to Cry" in 1978.

[12] In 1975, Hubbard and Sal Bando, a third baseman for the Oakland Athletics, won the American Airlines Golf Classic, which featured pro football and baseball stars as partners, in Palm Springs, California.