Pentagelli vs Clemenza

I've read that Pentagelli in this movie was originally meant to be Clemenza in the script, but it was changed to a new character due to the actor (Richard S. Castellano) not being able to return. I have to say, I'm really glad things worked out the way they did.

I have a really hard time believing Clemenza would ever have testified against the Corleone family. As we saw in Part I, he's very close to Michael and serves as a mentor to him, teaching him how to fire a pistol for his first assassination. He's almost a second father to Michael. Thus, if it had been Clemenza who was attacked by the Rosato brothers, he would never be tricked into thinking it was Michael who ordered the hit. And even if he did believe it, he still would never testify against them as he had way too much loyalty to Tom Hagen and the entire Corleone family, whom he watched grow up. He was at the Corleone family home almost every single day throughout Part I. And as we saw in the flashbacks, it was actually young Clemenza who first brought young Vito into a life of petty crime. Clemenza clearly was close to Vito. Had it been Clemenza caught by the police, I honestly would see him serving a jail sentence before ever ratting out Vito's children, even if he hated Michael the entire time he were doing it.

Pentagelli works much better and plays better dramatically. Because he's first introduced in Part II, he's more of a wildcard character, and even though he initially seems loyal to the Corleones, we're not as sure. We the audience have no idea how he will behave. His personality is much more unpredictable and unreliable than Clemenza's, and so it works better for his plotline. Plus, Michael V. Gazzo just gives such a great performance.