I don't recall Rocky using his jab often in his fights, but I've seen footage of him sparring and training, and his jab looked hard. It was literally rocking his sparring partner's head back upon impact. Rocky's jab reminded me of a miniature Sonny Liston jab. Does anyone have any more footage of Rocky planting his jab? And why do you think he didn't use it often in the ring? It was powerful in the training footage I saw.
Rocky used the jab as a weapon against Walcott in the first fight. Also thown the jab as a feit for the ko. Ezzard Charles I and II and a few others. He didnt used it much, but it did get the job done if he needed it, It getting close. Its not a Holmes jab or even a great jab, but Rocky used it to effect when he used it.
He used the punch and it was effective in setting up other punces. Rocky did not have a long reach but he used the jab at his range and it was a usefull tool in his arsenal