It's just a number I found interesting, no assumption on my part.
In the column, it did have some quotes from Steph White (the column was VERY Fever-centric, as is Jenkins's wont) in which she said that rough play does lead to players acquiring different habits. They plant differently, move slightly differently if they expect to be hit, etc. I actually heard the same thing on NPR yesterday in the context of Achilles injuries in the NBA, this from an orthopaedic surgeon who studies and treats Achilles injuries. I dunno that White was saying there was a cause and effect, but the surgeon was definitely saying it wrt. those injuries.