Carson High's wrestling team started practice Tuesday as the four-time defending Sierra League dual-meet champion.And, with nine wrestlers, who saw extensive mat time last season, returning it won't be easy to stop the Senators this year.Topping the list of returnees are 132-pound Cole McCarthy (31-4 and 25 pins in 2011) and 120-pound Kyle Sharp (37-10, 29). Both wrestlers placed fourth at last year's state meet.Three other state meet participants also are back: 113-pound Sam Mercado (22-15, 11), 170-pounder Jordan Luhrs (20-13, 15) and 182-pound Brady Rivera (13-14, 8).That's not a bad nucleus to start with. And, when you throw in …