Pernell Whitaker. Honorable mention and by far not atg status here but, Chris Byrd did pretty well for himself (for a while) with zero power and fighting well above his weight class. He was never the same after Ibeabuchi though.
No idea. Probably some aggressive guy I've never really seen, like henry Armstrong. Julian Williams was real good against Hurd.
Jack Johnson was well known for chatting with ring-siders whilst controlling his man, smiling and lasting many more rounds on a far more regular basis than any fighters mentioned so far. He was not so offensive in close as a Duran for example but the question only asks for defensive fighters. He was pretty revolutionary in this regard.
Exactly! To me "in the pocket" means to be near center ring, not on the ropes or holding and clinching where say Mayweather does a lot of. Strictly being defensive and not a lot else I'd say Pernell Whitaker was the best I've seen and I've been a boxing fan since 1980. As some in this thread have mentioned, fighters like Duran and Chavez were great defensively and imo capable of being just as good or even better than Pernell Whitaker if they chose to play it as cautious as he did. We can thank the heaven's they didn't as the sight of a fighter with the head and waist movements of those two while still being offensive minded and vicious is just a sight to behold.
Think how great Toney would have been if he had been consistently disciplined in and out of the ring.
Mayweather was very hard to hit while pinned on the ropes. Leonard did well to avoid getting hit in the pocket v Hearns while landing fast hooks in their first clash.
We definitely saw glimpses of his very best at times. But he had a lot of fights that were decided by a single point. Dave Tiberi actually outfought Toney on the inside. Many years later Toney admitted that he lost that fight. (honestly, it could have gone either way) Then years later Toney absolutely butchered Barkley.
James Toney was not the best defensive fighter in history since he got hit a lot in any fight. He got hit cleanly but he didn't even flinch. That's what he was. The best chin fighter in history.
Mayweather, he hardly ever seemed to get hit. Although too early to say but Ted Cheeseman will be in these conversations by the end of his career.