Rentzel was a four-sport star at Oklahoma City’s exclusive Casady School, playing football, basketball, baseball, and running track.
[3] He was a versatile all-around halfback and was known for his open-field speed and propensity for big plays rushing, receiving passes, and returning kicks.
Rentzel, offensive lineman Ralph Neely, Jim Grisham, and Wes Skidgel had signed with professional teams before the game and were ruled ineligible for the contest.
[9] Rentzel played sparingly as a backup running back due to recurring injuries and his contributions came mainly as a kickoff returner during his first two seasons.
He set the record for the longest kickoff return (101 yards) in franchise history as a rookie, which was broken by Aundrae Allison's 104-yarder in 2007 and Cordarrelle Patterson's 109-yarder in 2013.
Rentzel also starred in the 1967 NFL Championship, known since as the "Ice Bowl", scoring a fourth-quarter, go-ahead touchdown later negated by the Packers' game-clinching drive.
[19] Rentzel missed the last three games of the regular season, including the Cowboys' playoff drive to its narrow Super Bowl V loss to the Baltimore Colts.
On May 19, 1971, Rentzel was traded to the Los Angeles Rams in exchange for tight end Billy Truax and wide receiver Wendell Tucker.
Head coach Tom Landry said after the trade, "We know we are giving up on one of the top flankers in the league, but I thought he would be better off in another city where he had the same opportunity regularly.
In 1973, while on probation for the indecent exposure charge, Rentzel was suspended indefinitely by the NFL at the start of the 1973 season for conduct detrimental to the league after being convicted for possession of marijuana.
In January 1975, Sport Magazine editor Dick Schaap hired Rentzel and teammate Fred Dryer to cover Super Bowl IX.
Donning costumes inspired by The Front Page, "Cubby O'Switzer" (Rentzel) and "Scoops Brannigan" (Dryer) peppered players and coaches from both the Minnesota Vikings and Pittsburgh Steelers with questions that ranged from the clichéd to the downright absurd.