Isbell attended Little Cypress High School, before moving on to the University of Houston, where he was a team co-captain as a senior.

Isbell was selected by the Houston Oilers in the twentieth round (159th overall) of the 1962 AFL Draft, but instead chose to sign with the NFL's Dallas Cowboys as a free agent in 1962.

[2] On November 3, 1963, he suffered a left knee injury against the Washington Redskins and was lost for the year.

On August 15, 1966, he was traded to the Cleveland Browns in exchange for a fifth round draft choice (#127-Zeke Moore).

Isbell was selected by the Cincinnati Bengals in the 1968 AFL expansion draft from the Houston Oilers roster.