Murray used the high guard defense a lot like Stevens and for much of the fight it resembled the Stevens fight. At the same time the difference was he respected Stevens power more so he kept at a good defensive distance from Stevens. For Murray he threw a lot of uppercuts instead of the jab and used the overhand left that KO Rubio. The best defense for his opponent seems still be ducking and bob/weave. I think one thing is certain, with the high guard GGG has the tactic to not burn himself out as about 50% of the punches are only probing or setup punches.
I don't think it's necessarily the tactic but how well it is executed. The thing that I liked most about GGG in this fight was that he wasn't easy to clinch, that didn't work very well against him.
Yea that overhand left is rare stuff man, throws it like a right almost, makes me wonder if he might be ambidextrous? Anyways masterful performance by GGG and valiant effort by Murray.