After a 4-1 defeat at Park Island the previous Sunday, a four-goal margin away to qualify for the finals was always going to be an insurmountable task.
Greatholder bemoaned the statistical odds, stepping into the realm of what-ifs after their demise on a 10-5 aggregate loss.
"We would have won the game today because on a normal day [round-robin phase] we wouldn't have had to go out to score four or five goals.
"We could have been 3-2 or tried to win 2-1 but it was pointless," the coach said proud of his troops who made history as the first Bay franchise side to make the premiership playoffs.
While the game had an under-12 look about it, Greatholder said the Bay were "in complete control".
Waitakere striker Roy Krishna drew first blood in just the second minute before the golden boot went on to claim a hat-trick (42nd, 68th).
To the visitors' credit, they equalised through a Cole Peverley penalty in the 21st minute and a Conor Tinnion goal in the 27th put them up before going into the breather locked 2-all following another penalty kick from Peverley.
In the 59th minute Matt Cunneen nudged the hosts ahead 3-2 before Stephen Hoyle's equaliser two minutes later.
Ryan De Vries made it 4-3 three minutes later before Jake Butler sounded the death knell in the 77th.
Bay reserve goalkeeper Danyon Drake made his debut in the 80th minute after veteran Richard Gillespie took a body blow from a free-kick following a foul pass back.
"The ball struck him on the face at point-blank range so he was a little concussed," Greatholder said.
Waitakere play Auckland City in the final this weekend after the latter's 3-1 victory over Canterbury United in the second leg yesterday.
Result: Waitakere Utd 6 (Roy Krishna 2nd, 42nd, 68th; Matt Cunneen 59th, Ryan De Vries 64th, Jake Butler 77th) HB Utd 4 (Cole Peverley 21st pen, 48th; Conor Tinnion 27th, Stephen Hoyle 61st).
Halftime: 2-2.