I know we are only 5 weeks into the season, but at 1,759 yards, Philip Rivers is on pace to throw for over 5,600 yards. His schedule remaining with rank vs. the pass is as follows: @StL (22nd), NE (28th), TEN (27th), @ Hou (32nd), Den (16th), @Ind (13th), Oak (10th), KC (25th), SF (21st), @Cin (14th), @Den (16th). It's worth mentioning that the best pass defense he faces is Oakland at 10th, whom he just shredded for 431. His first 5 games were against KC (25th), Jax (29th), Sea (31st), AZ (26th), Oak (10th). It would be hard to manufacture a much easier schedule over the course of the year.
Worth noting is that Kyle Orton is not far behind Rivers and has a very similar ridiculously easy schedule being in the same division. It's quite possible that they both break Marino's record in the same year.