A couple of years ago some friends and I arrived in Australia less than a week after a category 5 storm blasted the northern barrier reef. Our liveaboard was the first to visit some of the sites after the storm. I thought things looked pretty bad, but I was comparing it to the last time I had dived there, which was about 12 years before. About a year later, I saw a documentary on that storm. By an amazing coincidence, Google Earth had come through only a few weeks before the storm and videoed the reef using their 360° camera. They came back and did it again after the storm. The impact was indeed tremendous.
Similarly, I dived Cozumel not long after Wilma, and some of the shallower reefs had been badly hit. One of the most popular of the shallow sites was, IMO, mostly a sand pile after the storm.
As for the Keys, remember that a number of years ago, Hurricane Dennis, not a remarkably big storm, took the 510 foot ship the Spiegel Grove and turned it from lying on its side to sitting upright. I would expect that Irma to have had some effect upon the shallow reefs.