The first half was just about the messiest 40 minutes of the season, with the breakdown a shemozzle, the scrums taking an age to set properly, and the Steelers coughing up the ball at a disturbing rate.
Jordan Taufua, wearing the No7 jersey, crossed to give some hope to the home fans at 11-15.
The complexion of the game, however, changed on the Ioane call and Vaka cut loose off turnover ball, setting up Sione Molia and Sherwin Stowers for tries. Bay of Plenty looked stunned until restored to their complement of 15 and finishing over the top of the home team.
Counties Manukau have just a short turnaround, travelling to Hawke's Bay for a Thursday night Premiership clash, while Bay of Plenty host Otago in Tauranga next Sunday in the Championship.
Counties Manukau 39 (Jordan Taufua, Viliame Rarasea, Sione Molia, Sherwin Stowers tries, penalty try; Piers Francis 4 con, 2 pen).
Bay of Plenty 34 (Monty Ioane 2, Hugh Blake, James O'Reilly, Regan Ware tries; Kelly Haimona con, pen, Te Aihe Toma 2 con).
HT: 11-15.