It's a pretty straightforward stat that averages out, so number of reps isn't really too much of a factor. Of course, I'll still grant that when you have a smaller sample size, the numbers still can skew somewhat because it's easy to either perform abnormally well or abnormally bad over a small stretch. But in seven games, Purdy has had quite a few dropbacks, so I think any observable trends can be considered fairly reliable--moreso than, say, if he only played 2, 3, or 4 games.
And sorry if that seemed snarky. But I was responding directly to you calling me out out of nowhere for merely presenting a stat, saying it was interesting, and wondering out loud if/how it will come into play. My post doesn't "make a definitive conclusion" about anything. As I said, it will be interesting to see if/how that comes into play. And if it bears out, as I said, it "could" make for a high scoring game. Not sure how that's somehow controversial. High QB efficiency means the passing game is productive. And since they 49ers also typically have a very productive running game, coupled with Philly being weak on defending the run (if I recall, they are 22nd overall, although if you consider only the games after they acquired Suh and one other guy to bolster the running game, they moved up to 15th during that span), the run game is likely to be productive. That's a decent big-picture explanation for how there is at least a decent likelihood that both phases of the offense could be productive tomorrow, thus producing the likelihood of a high scoring game (and it partially explains why the 49ers are the #1 scoring offense during the span of time after McCaffrey was acquired and began starting).
Again, seems like a pretty straightforward, logical argument to make, so not sure why it got called out so aggressively in the first place.