Then why wasn't the same first-half to second-half discrepancy observed earlier in the season as well?
It was. Let's do this. In 17 games, Miami scored 2 TDs in the 2H only 5 times (I'm excluding DEN an an outlier). Those 5?
TEN - the 2 TD drives were 7 and 12 yds.
KC -
CAR - nuf said.
NYG - nuf said
WAS - nuf said
NE - 2nd game - 1 TD was a 27 yd drive
That's it. 6 games with NO TDs in 2H.
Now, let's move on to length of drives. I'm arbitrarily using 6 plays as my cut off. In the 2H of 16 games, only 5 games did Miami have two or more drives over 6 plays. Three times they had ONE drive over 6 plays and once ZERO drives over 6 plays. And keep in mind that generally means very few 1Ds. Also, for reference, in 4 of those games Miami entered the 2H with a lead - less pressure on the OC.
Those numbers are over the entire season. That, IMO, is horrendous. Those stats can't be explained by injuries or mistakes and it's hard to imagine TT having a 'bad' game in every 2H and overwhelmingly only the 2H.