Here's two .. 1. Jack Dempsey ... he got hit, lost his head, saw red and charged kamikaze ... he had the physical skills to fight like a Duran or a Paq but lacked the brain .. 2. Joe Louis .. watch how many fights he became puzzled, lethargic, won on overwhelming edge in talent but was extended without making the transition in the ring during the bout .. however, reprogrammed he crushed the guy ..
I'm going with Wilder. After the rematch with Ortiz he tried to explain how he set Ortiz up for the ko. His analysis was so far off and completely at odds with what we saw, I just have to assume he doesn't know what he's talking about but he has dynamite in his fists. Tbh, I think it's quite rare for a boxer with poor ring IQ to get to any kind of notable level.
How about Low IQ in general? I have an oddball. A Super Lightweight named Steve Hearon who beat Bruce Curry and then rising Sal Lopez and was the #1 contender for the title. His manager begged him to sit tight and wait on the shot, but Hearon booked himself in a fight against full fledged Welterweight (and big at that weight too) Lupe Aquino for 10K and gets beat like a drum. One more quick loss against a complete scrubbie and he never fought again. Of course getting convicted of killing three people does tend to put the brakes on your fistic career...
Joe Fraizer. Non-existent ability to even try something different when clapping his hands and coming forward face first isn't working. He was really good at what he did do well though.
Didn't read through all these pages to see if it's already been mentioned, but to say a Jeff Harding for example has a low ring IQ seems to assume the level of physical ability needed to carry out a "smarter" fight plan. That's not the case here or in frankly many examples. A Jeff Harding by definition isn't going to do much but plod forward and try to take your heart away. Bless him for that.