Which kind of gets at the crucial methodological question of this really interesting study (not adding anything new here): it's really hard to tell whether a player is capped versus what's due to a slowing of training due to age
If the age slow-down was a known-variable, maybe something more substantive could be said about how to pick-out capped players.
Right, and with that comes the definition of "capped": since it's a soft cap, this means that when a player is close to the cap, training slows down progressively. So the question is when exactly do we count the player as "capped".
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."