How to deal with a Mayweather defensive styled boxer?

I spar in 18 oz gloves and I'm not sure what caused it; but when I was sparring our Super Heavy he was pounding my left shoulder and it made it very hard for me to jab.

 

Perhaps him being a super heavy had something to do with it. Seriously I block punches with my shoulder on purpose. If my opponent decides to "wear me down" by hitting my shoulder, he's doing exactly what I want. That's the reason my face is behind that shoulder in the first place. I never noticed any wear down at all from being hit on the shoulder.

 

It's like doing a chin test between my shoulder and my opponents head. I'm taking my chances on that one.