I agree, his jab would be key. But he'd have to do that for 12 full rounds and again, I just gotta go back to his fight against an unskilled Chavez who did pretty much everything wrong (not cutting off the ring, no defense, being predictable, etc.) and it still took nearly everything out of Martinez to get that win. I think Golovkin has shown that when he touches his opponents, it hurts and it wears guys down. Martinez would have to use a ton of energy bouncing around the ring and imo, eventually he's going to slow down at some point and that's when Golovkin's heavy hands become a major factor. I think it's a lot tougher of a fight then some people might realize, GGG isn't hype job Chavez, he has real boxing skills and the amateur credentials to prove that (nearly 400 fights beating guys like Andre Dirrell, Andy Lee, Lucen Bute, etc.).
And you're right about Martinez, I'm not sure he fully recovers from his injuries either. I think he's 38 years old now. I guess we'll have to see how he looks against Martin Murray but I'm guessing we'll never see a prime Martinez again (nor do I think he'll fight other top guys like GGG, Quillin or Pirog).