I don't know -- I almost want to reject this label and notion of late bloomers. Part of the problem is that all kids develop differently. Some get teeth sooner, some walk sooner, some read sooner, some hit 90 mph on the radar gun earlier. The issue is that most never hit 90, clearly. But, also, most give up along the way...
The kids who are taller, stronger, physically more developed SOONER often have an advantage in most sports. So is a late bloomer a late grower? Or is a late bloomer one who consistently improves until they reach "that" level (starting, hitting certain measurables, not riding the pine, not getting cut, whatever)?
One son (2014) was a 5'10 140 lb freshman soaking wet. When he graduated he was 6'5" and 190. I know the coaches in 9th grade would have loved to have known he was going to get that big.