Whatever it is, any criticism needs to be held till he has played for the Phoenix, within the Phoenix structure and game plan.
I'm pretty sure there are plenty of cases where a player has not worked so well in one team, under one manager but after transfering has looked awesome. And vice-versa.
Thats not to say that Bertos has even been crap for the Glory, or will be awesome for the Phoenix, we will have to wait and see.
And just because a player comes off contract it doesn't mean Perth didn't still want him. Players come off contract and evaluate their options. As it is Bertos had the option of returning home to be under his National coach, close to his family so favoured the Phoenix contract. Pretty fricken simple (and common sense) if you ask me, but still speculation so take what you will.
Bertos has looked pretty good in the All Whites under Ricki, and I reckon he will thrive being home, with some of his good mates (Christie plus others I'm sure).
I'm sure everyone here will admit he's sh*t if he doesn't perform this year, and I damn well hope you knockers come back and face the music if he turns out to be awesome.