If the press is correct when does the 12 months finish?
"The Wellington Phoenix's 2019/20 roster is beginning to take shape, confirming the signing of German midfielder Matti Steinmann on a 12-month deal." FRI, AUG 9•SOURCE: 1 NEWS
Had a look using Wiki. Prone to error no doubt, but just compared 2018-2019 squad verus 2019-2020 squad. Transfer In & Out.
All of the players on one years deals who left - didn't technically stay a full calendar year (12 months).
Eg Mandi signed 12 October 2018. Released 13 May 2019.
All players were released in either May or June. Except Nicholls & Way who were released earlier.
Release dates otherwise start just before the 2019 A League GF (19th May 2019) - so maybe players can start to be released from a FFA/PFA mandated time, near normal season end.
https://en.wikipedia.org/wiki/2018%E2%80%9319_Wellington_Phoenix_FC_season
https://en.wikipedia.org/wiki/2019%E2%80%9320_Wellington_Phoenix_FC_season