In Val's latest article he mentions these two players as possibly joining Adelaide.
Merkel is a particularly interesting prospect, only 25 years old but he debuted and started for AC MIlan as an 18 year back in 2011 when it looked like he was going to be a star. He has clearly fallen well short of those early expectations but still could be an excellent A-league CM/AM. He could fit in beside Isaias in a 4-2-3-1 or more likely as the AM in the same formation. 
Avaridis is an experienced winger/striker who could fit onto the RW or even AM in behind Baba. 

Also Carrusca is said to be signing for another club, Melbourne City, or making Brisbane even older?

http://www.adelaidenow.com.au/sport/football/a-league/teams/adelaide/adelaide-united-tracking-two-more-foreigners-for-the-new-season/news-story/92e7d54eaca92eb119b8fe30acc76a74