Why does my opponent keep pausing?

The match starts and he immediately pauses the game.

He scores and he immediately pauses the game.

It doesn't look like he's making any subs while paused. I don't have any way to tell whether or not he is adjusting his tactics. But I will say that it feels like he plays much better and I play much worse afterwards.

What is the purpose? Is he trying to frustrate/psych me out? Or is he doing something else?