Morale.

[Sully]

True this. I had players loose moral. Maxed them again after a match. Next day, again morale loss without playing. Lesson learned is only to max morale just before playing. Morale is dropping a lot faster, even after winning 3 games in a row.

that is the best method, only give morale packs before the game.

Morale drops after the daily restart
Morale drops after every game for most players that get ratings under 8.