there is one particular picture of Jake, I think it was a coloured picture too where Jake's Dome does look like a Bobble Head for the back window in your car. didn't Graziano call him Old Cement Head in their reflective interview together... did he mention too that they quarrelled as kids in the Streets, I can't rightfully remember now. I'll see if I can find the link for it!
If head size was important they would’ve included it in the old Tale of the Tape. Imagine that. Never heard a commentator say “He’s shorter, outreached and outweighed but that freaking huge head of his is a major advantage and is gonna be a tough obstacle to overcome.” If anything, overly large, super massive heads might present as a bit creepy - perhaps good for intimidation purposes only.
Larger skull means more bone mass to protect the brain. It also means it's more difficult to damage the skull. Doesn't always mean you have better punch resistance or durability due to a larger skull, but I believe overall there likely is a correlation between the too. Especially if you have a well built neck. Amir Khan has a rather smaller skull and that boy has no chin .... Chuvalo had a large skull and he had an excellent chin. But then you have people like Oliver McCall who seem to have average sized skulls in comparison to their bodies and have legendary punch resistance. Hagler had a normal sized head for his body but had legendary punch resistance ... But he also had a very thick anatomically built skull apparently. It seems to be that the more bone mass you have the better protection and resistance you have .... But size doesn't always mean density .... Although I may be wrong since its hard to tell how big someone's head is on film versus reality ...