Prime Calzaghe vs Golovkin

[Primo Carnera]

Calzaghe looks naturally too big for him. Then throw in his speed, unreal engine, punch output, granite chin (a few flash knockdowns in nearly fifty fights), adaptability and unique style - GGG has got two hopes.

Young Calzaghe TKO.

Old Calzaghe UD.

I'd agree with all of that except the TKO.
Let's not forget that any time GGG Has been hit hard (and he has from time to time), he's just walked through it.
Calzaghe UD All day long, young or old.