Examples of a boxer(s) using great judge of distance...

Wlad is a very very good answer. His control of distance is spooky. Of course, we have no idea how he would do against a durable swarmer or a master boxer or a fighter with similar judge of these details, but his skill in this area is undeniable.

Ken Buchanan is very very good. He moves a great deal, a very mobile style, and if he wasn't a superb judge of his range he couldn't make that style work, never mind its becoming the cornerstone of his greatness. Some of his moves were exaggerated uneconomical and unnecessary, but he rarely failed to get the distance right.

[ame]http://www.youtube.com/watch?v=RfVKFjbZLGE[/ame]

Morales was very good in this regard. He made a HOF career out of going away from aggressive opponents and timing them perfectly with a one-two or just the one or just the two. I wouldn't go so far as to call him a one-two artist, but Kelly Pavlik could definitely benefit from studying the guy

[ame]http://www.youtube.com/watch?v=ZbyosYCPjps[/ame]

But the best of the modern era is Hopkins. Against Pavlik, he basically won the fight on critical judgements of range, creating range, creating angles. That's the one modern performance that sticks in the mind beyond all others in this regard.

[ame]http://www.youtube.com/watch?v=Nu9AXWp1jYY[/ame]

 

That's more judging distance on the heavy bag, no?