The Conundrum of Joe Allen

While i'm all ecstatic and flying through the roof... I'm still incredibly confused as to how Joe Allen was used over both legs.

Each time he came on, Klopp deployed him behind the front line. He's a DM, right? Can someone explain that?

I figure it's to create a disruptive defensive presence high up the pitch but...is that it?

I'm so confused.

Happy, but so, so confused.