It can go in both directions. I am sure of one thing - Briedis has never faced a puncher like Shavers, and that fact is not to be underestimated and neglected.
Mairis is too smart and defensively tight to get caught by a big Shavers right hand when that would be the only thing he would be focused on for the whole fight. Shavers was a one-trick pony and Mairis was never dropped so I think it's safe to assume his chin was sturdy.
Shavers was on him throwing left right combinations the whole round, dropped him the first time with a left to the head and a right to the body, and the second time for the stoppage with a right uppercut. If you go back and watch that one round you can see that Norton took many lefts to the head and didn't crumble until he was hit with Earnie's right.
He dropped Ron Lyle with a left hook too. Of course Lyle rose back up and wore Shavers down to stop him a bit later but Earnie could punch hard with both hands