They don't. That's the point. We need eight "homegrown" players in our squad - since Jones counts as homegrown (unlike our other keepers) he'd be able to take up one of those slots. A "homegrown" player is a player who played for an FA affiliated club for three years prioer to thier 21st birthday. You can have as many under-21s as you want, but they don't count towards the eight homegrown player rule.