Jay:
Love went 66 three of his four rounds at WF, although some might argue that the PGA set-up may have had something to do with it. I do think length -- not just overall length, but the shortness of some holes at Oakmont (all of this discussion is pre-06 WF and pre-07 Oakmont) -- lends itself to perhaps more birdie opportunities and less strenuous par holes. WF played 6930 in '84 (par 70) when Zoeller won in '84, compared to Oakmont's 6972 (par 71) in '83, when Nelson won. WF played 6987 in '97 (par 70) at the PGA, compared to 6946 for Oakmont in '94 US Open (par 71). I distinctly remember Nicklaus shooting an opening 69 at Oakmont in the '94 US Open (age 54!), only one stroke off the lead, and someone asked him how he did it. He said (paraphrasing): Well, it's not that long of a course.
Having never been to either course, WF strikes me as demanding long iron after long iron approach for nearly the entire round, where Oakmont has more of a mix of holes, short and long, and thus (combined with one more par 5) the opportunity to use a short iron for at least a few approaches.