UCLA's offensive leaders in 1970 were quarterback Dennis Dummit with 2,392 passing yards, running back Marv Kendricks with 573 rushing yards, and wide receiver Rick Wilkes with 595 receiving yards.
In his final season at UCLA, Prothro's team suffered a rash of key injuries and finished 6–5, yet they were three close games from a 9–2 season and Rose Bowl berth. Before those injuries set in, UCLA took a 3–0 record into Austin to play defending national champ and top ranked Texas. Trailing 13–3 at the half, UCLA rallied and had a 17–13 lead in the final minute. But with 12 seconds left, Texas completed a long pass when their receiver caught the ball between two UCLA defenders, who then collided, allowing the receiver to score.
UCLA also blew a 20-point fourth quarter lead against Oregon, when Ducks sophomore quarterback Dan Fouts rallied his team to three touchdowns and a 41–40 win.
Finally, there came the showdown with Stanford; the game was expected to be a shootout between UCLA quarterback Dennis Dummit and Heisman winner Jim Plunkett. But the defenses ruled as UCLA took a 7–6 lead into the 4th quarter. Stanford took a 9–7 lead on a field goal, but UCLA was driving to a potential game-winning field goal or touchdown themselves when they completed a pass inside the Stanford 10-yard-line, only to have the receiver get sandwiched by two defenders on the tackle and fumble. This game ultimately decided the Pac-8 championship and 1971 Rose Bowl representative.
The season ended on a high note when UCLA beat rival USC, 45–20, in a game that was not that close. This would end up being Prothro's final game at UCLA.
Prothro was frustrated by bizarre officiating at critical moments, numerous last minute narrow losses, and losing out of the Rose Bowl by the conference vote in 1966. Prothro also decried the Pac-8 rule that only allowed the conference champion to go to a bowl game; he witnessed many lower ranked inferior teams (often ones he defeated during the season) go to bowl games while his Bruins stayed home. After George Allen was fired by the Los Angeles Rams, Prothro accepted that job.