I'm assuming he's meaning that if soccer didn't have 'offsides' and you choose to leave a few guys back, it would be a similar situation as a power play in hockey as far as 5 on 4 etc.
That's wot m8
except by mentioning hockey he must understand why hockey has an offside rule and that same logic can be applied to soccer.
also power plays are punishment for players on the other team doing bad things, soccer has this same mechanic with red cards, except unlike in hockey, the team doesn't get their player back
m8