Arnold would have beat Sergio from '73 to '75 but not in '72.
Can't assume that-Schwarzenegger was in his best shape 73-74 only because he expected Oliva to be there, and
only after Schwarzenegger refused Oliva's challenge to come out of the audience to compete against him in a neutral, non-Weider contest. Essentially Schwarzenegger backed down, which no one realizes.
If Oliva had the cuts in the contest that he had days after after the contest, he'd have won no matter what. Lacking a little sharpness made it a toss-up.