You make a fair point, but...
I'll play devil's advocate. Numbers are great and all, but even statisticians know they aren't the only part of a complete analysis. (At least the ones I've worked with in biomedical research seem to think that way.) WR play is largely dependent on the QB and offensive schemes (whether it be route trees, play calling, or the simple ability to move the ball, run more plays and be effective enough to have balance). Even something like YPC, and for that matter YAC, has some dependency on the QB to put the ball in the right place at the right time to give the WR a chance to catch the ball and get yards.
Philly has played with Jim Bollman as an OC and Joe Bauserman at QB. The coaching changes also didn't help and Braxton Miller wasn't exactly slinging it around his freshman year either. Didn't OSU win a game where they had one completion that year? I grew up idolizing guys like Terry Glenn, Joey Galloway, David Boston, and Ginn. Even I in those younger years could recognize comparing those situations for those WRs to the one Philly has played in is not a fair comparison. Going from total completions to stats like average yards per catch is a step up, but it shouldn't be considered ironclad for a complete analysis. Indeed, it is ignoring confounders such as QB play and team offensive performance, as well as the unquantifiables such as the coaching situation (though it can be reflected somewhat in team offensive numbers and rankings as additional variables). Multivariate analysis that included how well the QB performed while comparing WR performance would surely paint Philly in a brighter light more comparable to the noted former OSU WR legends. Not to mention that saying the comparison of Philly to these other guys is a four years to three years comparison is laughably dishonest. Philly had a whole year where there was an interim head coach, Jim Bollman in the driver's seat of the offense, and shared snaps between Joe Bauserman and a freshman year Braxton Miller, and oh by the way, no worries because the QB coach was a video coordinator. Show me one of those 30 other top pass catchers that had a year with a situation anywhere near that bad. Without looking I would bet that most of Philly's numbers come from this year and last year. As you said, imagine the numbers Philly would have had with a Troy Smith or Joe Germaine, and surrounded by other offensive threats, and without coaching turnover and ineptitude, plus without a year like that to bring down his averages because the team was lucky enough to complete a Joe Bauserman pass when they weren't running Dave or their best 3rd down play, Braxton on a QB draw.
The claim that Philly is not a difference maker or game changer is not in line with any objective measure, it's subjective. As I stated above it's also selective (and also lacks the kind of perspective that makes the size of the fish you caught grow over the years), and I think this bears repeating: Philly had a 68 yard punt return touchdown in a game where Ohio State managed one offensive touchdown. Without that score there likely wasn't an undefeated season last year.