Oh, look. Only one Ret Paladin as well. They probably would have replaced it if they had the chance.
If you look, the only dps they have more than one of are Demo Warlocks, Fire Mages, Balance Druids, and Ele Shaman.
Every other dps spec was either not represented or only had 1 in the group. There were no spriests in the group, for example. Just because your class wasn't used, that doesn't mean it's bad. Hell, if being underrepresented meant that your class needed buffs, Ret would have had the most buffs in every patch note from TBC to mid-Cataclysm.