According to Rudan post PG v SFC game. Rhys Williams is unhappy and may look to move on. Sydney FC have expressed interest

Adelaide please.

Hasn't he been poor? 

yes, and still not fit,  missing 30% of matches at the moment..  

Rumour doesn't make sense,  SFC squad are not short in any of the positions he plays (CDM or CB or even RB), and with no Champions League they do not need the reinforcements.

CCM or Adelaide on the other hand makes more sense, even WSW

http://www.fourfourtwo.com.au/news/sydney-jump-the-gun-on-rhys-williams-445071

I'm guessing that he was just one of many players Sydney were aiming to talk to, keeping the options open for who they sign for next season. With 12 players off contract there's a lot of potential room to retain or replace.