He never worked with Scorsese before The Irishman

It is hard to fathom.

Pacino's not as associated with crime dramas in the way that De Niro, Keitel and Pesci are so there may not have been an obvious fit between the two for a lot of Scorsese's films.

I hadn't thought so either. I was reading an article making a big deal about their getting together again with Scorsese and I was like... huh? That was Mann. That was DePalma. That was Coppola. The article writer was clueless.