Now that I'm home and I can explain this more here's what upsets me about it.
All of the minutia about weather and turf aside, the calculation boils down to Speed vs Speed. While this makes sense if you're talking about a clear differences in player type and position, Speed vs Speed only occasionally makes a difference in WR and CB interactions. Otherwise, Tyreek Hill would be a 2500 yard player.
If I'm a CB and I'm playing someone that I know is faster, I have two options when in M2M (and really I'm only going to talk about M2M here since it's stupid to run deep zones against teams that run a lot of go routes in MFN unless you like to see your DBs abandon the play):
1) I can give the player cushion and sacrifice the underneath route so the WR can't go over the top.
2) I can play close and knock the WR off the line. And thus disrupt the WRs ability to accelerate to top speed.
Now, as a coach, I have multiple options for when to do either 1 or 2 above. I may exclusively go 2 Deep safeties and put the CB in B&R. That way if the CB doesn't make a clean jam, the safety is there for over the top help.
Or I may play 3 Deep man to defend it.
Now here's why this won't work in MFN.
1) I have no control over whether my CBs are in B&R or playing off.
2) I have a limited selection of 2 Deep, Cover 2 plays. And most of these are blitzes, so I have an even more limited selection if I want the LBs to drop into coverage.
3) I have an even more limited number of effective 3 Deep Man plays (there are only two that I run in specific situations). And, for that matter, there is only 1 decent 4 Deep Man Dime (I think it's Dime) defense.
4) Zone defense is so bad against deep passing teams that it's a liability.
5) Play overuse means that the effective plays that I have to cover these deep passing routes will leave me more vulnerable because defenses get called for play abuse more than offenses because, well, speed vs speed means that no other defensive attributes matter so my bad coverage becomes worse.
It's no wonder that the most effective passing offenses overuse the following plays:
122 - Medium passing routes where the WRs run go's.
014 - Medium crosses where the WRs run go's.
113 - All Go
104 - All Go
This makes a lot more sense now. And confirms my suspicions that I'm just playing Madden or Techmo Super Bowl or any of the other throw long every down games...