Loose-passive winning poker

[HarriSeldon]

I have a friend who has started to win on a frequent basis playing NLHE $0.15/$0.30. The strange is that his playing style is loose-passive.
He is not winning much but seems to have a little steady income from his poker. He plays 6-7 tables simultaniously and is getting some good rakeback too.
He has a fish symbol (loose-passive/passive)in Poker Tracker given by the default auto-rating system within PT.
It becomes even stranger when you get to know that he plays mostly on shorthanded tables. He has not changed his style lately and started to win thereby. Loose-passive is really his style. He has winning figures for over 200k hands with that loose passive style. My question is: how is it possible?