Sugar Ray Leonard and Ali come to mind immediately. Maybe this example doesn''t fit this thread exactly, but I always enjoyed reading of how someone once asked Willie Pep if he could win a fight without throwing any punches. Pep agreed to deliberately throw no punches during one particular round of a fight, just to see how the judges scored that round. All three officials scored the round for Pep!
No mention of Chris Eubank yet? The man made a career out of fighting the final 30 seconds of a round, to sucker/trick the judges. You could argue he was simply the best at it.
I think most conclude, and the lack of evidence suggests that is an urban myth, all be it a very clever one.
In Peter Heller's In This Corner Willie Pep states that he won a round without throwing a punch in his bout with Jackie Graves. He admits to "jabbing a few times but most of the round bobbing and weaving and making him miss and he missed a hundred punches..."
...jorodz beat us both to it, garfield old boy. gavilan practically made a career of it. best i ever saw.
Mayweather easily beat De La Hoya. DLH was the one who was flurrying (and missing) throughout the fight.
Sugar Ray Leonard and Muhammad Ali were the best at stealing rounds. Evander Holyfield should get a mention.