Someone explain something to me

Last week, we tie the game. Sjs marches down the field, scores to win game

Today, playing our rear off, take the lead, Aggies march down field to take halftime lead.

So seems to me one of two things are occurring. Either the defensive players relax, or our defensive scheme and tendencies are fairly well scouted by opponents and the scheme makes it easier for them to score.

Any thoughts?

Possible “two minute offense” mentality and it’s more the offense throwing something different at the defense than the defense relaxing?