A dejected Brendan Santalab conceded Western Sydney never bounced back from the shock departure of inaugural coach Tony Popovic a week out from the start of the season.
A missed penalty and a send-off helped snuff out the Wanderers top six hopes as they fell 3-2 to Adelaide United in an anxiety-riven match at ANZ Stadium on Sunday.
The loss of the must-win clash will only add to the pressure mounting on coach Josep Gombau who was appointed in November.
The game was poised at 2-2 when super sub Santalab was beckoned off the bench to a deafening cheer from the crowd.
Instead it was Adelaide, through substitute Ryan Kitto, who scored the decisive goal three minutes later.
Is this the goal that sets the Wanderers on their way to the finals?— Hyundai A-League (@ALeague) April 15, 2018
Don’t miss the second half LIVE on Fox Sports 501. pic.twitter.com/q4yKamkEbh
Post match Santalab told Fox Sports: “It’s tough, it's been a real roller coaster season.
"When Popa left it was very tough for us all at the club, players and staff, and I don’t think we ever got into gear during the season. We were up and down and never gained momentum or consistency."
In a see-sawing match Wanderers got off to the perfect start as Oriol Riera opened the scoring from the penalty spot (16').
Adelaide then took the lead through Baba Diawara (21') and Daniel Adlung (39') before Marcelo Carrusca headed the ball home for the equaliser (42').
But two key moments turned the match. Riera had the chance to put Gombau's men in the lead from the penalty spot but his effort on the cusp of half time was well saved by Paul Izzo.
Then, just after the hour, with the Wanderers on top, youngster Keanu Baccus had a brain snap that will probably haunt the teenager for some time.
Tangled on the ground with Johan Absalonsen he kicked out, buckling the Dane's knee, and earning himself a direct red after the intervention of VAR.
Boos rang out on the final whistle and Santalab said he understood.
"I feel their frustration," he said. "We have fantastic fans – 17,000, 18,000 of them – so to send them off like this is very disappointing. We’ll be back bigger and stronger next season but we have a lot of work to do."