Not particularly quick fisted or fleet-footed. A bit methodical in terms of approach and appears to have a tendency to head-hunt. (Which is odd because he's got a nasty hook down-stairs when he elects to use it. He hurt Proksa with pretty much the first serious one he threw, and set up the second kd as a result) At the moment, I think Martinez would more than likely be able to exploit these flaws better than anyone else in the division, because I think GGG might have some difficulty tracking down Sergio without exposing himself to counters on the way in. Still, it should be noted that GGG's defense in this fight was better than it was in previous outings, especially in close, and he made more of a concerted effort to jab his way into range. So, he at least seems intent on improving various facets of his game; and if this continues, then my opinion of how that match-up would turn out may very well change.
Gets a bit over excited at times looking for the finish and disregarding his D, and squares up his stance a lot. I could easily see a tricky fighter like Martinez just catch him coming in because Martinez is fantastic at setting traps looking to counter. But his beard seems sturdy so that might not even matter. :think
Just some slight defensive holes but a study chin makes up for that his speed is good but not great for 160lber But incredibly balanced and good leverage on every shot even his Jab