With four games remaining to decide the playoff, contenders Bay United face the onerous task of winning all of them or kissing this summer goodbye for a side who have made every cut under Angell's four-season tenure.
"We knew prior to the Palmerston North game that he was leaving," McKenzie revealed, adding Thurston intended to leave earlier but prolonged his stay until last weekend's game.
"He was another player we would have liked to have kept until the end of the season but, obviously, it's not the case and we'll just move on."
He said that's why the franchise was active in the transfer window by the January 24 deadline to woo Tinashe Marowa, Sam De St Croix, Jordan Lamb and returning Bay United veteran Danny Wilson.
Hamilton-born defender Liam Hayes slipped back to the Wanderers.
McKenzie said Ghanaian/American import striker Samuel Adjei's hamstring has been diagnosed and he was unlikely to play until round 16 against Canterbury United on February 25 with an O-League game break buying him some time while Auckland City FC and Team Wellington fulfil their obliogations.
The only other injury concern is Gavin Hoy who came off second best in a 50-50 tackle.
He said Angell would shuffle his pack to find someone to fill the void Thurston left behind.
Among the contenders are Hastings midfielders Karan Mandair and Bjorn Christensen who played in the central position for the Havelock North Wanderers in the Lotto Federation League during winter.