Posted this in the NFL forums. Cross posting here: https://nfl.myfootballnow.com/forums/4/2579?page=1&x=2s4DUnpAkG#11363

nfl stats dictate pass on 1st down.
There's ton's of doctoral thesis' out there as well as official NFL stats.
As for MFN?
defensive plays are too broke to get real data. Off plays are too limited in success to get real data.

I’m gonna toss this out there as a casual, not causal stat: pass plays seem to get more yards per play than run plays—even when the data is limited to only plays that “work” on offense versus the most commonly used defensive plays.

I’m guesstimating roughly 3.5 yards per run on average and 5+ yards per pass play.

Absolutely just scatting, Carruthers-style. A mental spreadsheet… HA!