Indeed, BB_Patrick answered earlier the question
Let me get back to you on this, but I'm 99% sure it also affects potential caps.
What that means is that if you have a player who has capped, and that player has at least some JR or some SB, then that player should revert back to "almost capped" again, where you can still train him.
Unless you continued training that player a lot even after he capped out.
"Air is beautiful, yet you cannot see it. It's soft, yet you cannot touch it. Air is a little like my brain." - Jean-Claude Van Damme