We've been assured there's no "keep it close" logic allowing for a multitude of highly improbably 4th quarter comebacks, but things like this seem to happen to me a lot: https://mfn67.myfootballnow.com/box/view/83

I took a 31-13 lead in the fourth quarter, having dominated in virtually every aspect. My four fourth quarter drives result in this:

2 plays, interception
2 plays, interception
7 plays, lost fumble
4 plays, interception

Meanwhile, a defense that had forced 3-and-outs for the past two quarters is suddenly helpless, giving up 80- and 78-yard TD drives, along with two short scores off the turnovers.

As always, it must just be a simple combination of gameplanning rules and fatigue allowing for the stark contrast in my pass offense and rush defense before and after the 4th quarter.

Without going down the conspiracist route, but I tend to agree with this and have thought this too for sometime. I'm sure games like this can happen, but when you totally dominate and completely capitulate...

If you figure out what it is let me know ... again, the only change that happens is the teams go into hurry up/slow down and so the play calling changes. Everything else has to do with fatigue or some other factor.

What I see time and again is as the OP said , a team DOMINATE 3 qtrs then all of a sudden completely forget how to play football and the other team seems to have their oppositions play book to boot.

I think it was Sethrick who had a melt down when this happened to him , (first time it happened to him) but as it happens that frequently you get used to it.
I have also to say that not every time a team will come back and win, but it does get close , that cannot be coincidence .

I notice this play, but not in my games to such an extreme. I can maybe think of a 21 point comeback out of all the games i have watched. It seems the only pattern is more plays happen in the 4 th quarter no doubt. I keep hurry up and slow down both at three or less and keep fatigue settings below 60. I do think those things are important. Along with a plenty of reserve players ready and set in the chart deep. Most of my games have lower play counts also. That is key here. I think?

It's difficult to put a finger on. I've seen too many examples of this for it to be coincidence or bad managing, but we've also seen many examples of runaway blowouts where no 4th quarter shift happened.

The only other thing I can think of is some sort of "ride lightning" effect at work, where momentum swings on a big play and carries a team for a while. It's possible that's happening at times throughout a game without being noticed, except when there's one big shift late in the game that never swings back the other way.

I think part of it has to do with how fatigue works. I've noticed that CBs get fatigued faster than any skill position. This is problematic in the 4Q when your opponent is throwing every down. You can dominate on first, second, and third down and then have your star CB decide he needs to take a breather and your CB3 or 4 allows a 25 yard gain to keep a drive alive. This is completely different than how fatigue works for QBs, OL, DL, and even LBs. So until the fatigue by position settings are in place, it's hard to maintain snap counts across positions.

Fatigue would certainly weigh on the defense when the offense is turning the ball over every other snap, but why is the offense suddenly turning the ball over every other snap, over and over and over and over again.

Some of it is definitely game planning. The default run out the clock mode is terrible. I ended up having to create a series of rules to get a good run out the clock offense. Another thing that is buggy is time between plays in the 4Q when a team is trailing. Here's a recent example (watch from this point on): https://mfn13.myfootballnow.com/gamecenter/view/2150#393033

My opponent gets extremely lucky twice.

First a penalty allows them to run two plays with no time coming off the clock in between.

Second my team clearly tackles my opponent in bounds with 5 seconds left and the player is called out of bounds stopping the clock to allow the game winner.

I think this is the main culprit. "Run the Clock" mode might as well be called "Try to Let Your Opponent Come Back" mode. It, along with the so-called "Hurry Up" mode, sucks.

I have turned it off for all of my teams because I have no desire to run the FB up the middle every play.

I also do not seem to have these Jekyl and Hyde 4th quarters very often, if at all.

Coincidence?