Phil, several of the long par 4s at Oakmont are long on the scorecard only - they play significantly downhill.
Case in point:
Thursday Tiger hit driver off the 1st tee, missing the fairway by a good bit, and started the day off with a bogey. Friday he hit iron off the 1st tee (his 10th of the day). Result: split the fairway, parred the hole. Even the 10th, where you note he missed the fairway with an iron, he was only in the first cut, up against the next cut, and made par.
Similarly, if one accepts the 670 yard 12th, the greatest hole in golf, as a 3 shot hole, the big boys could easily play it with an iron off the tee.
Does anyone know if Tiger has hit the fairway with his driver yet?