Hammered on the scoreboard and smashed from start to finish all over the park, Wellington's evening was further soured with serious injuries sustained by defender Reece Caira and Costa Rican international Kenny Cunningham, the visitors' sole goal scorer.
Caira suffered a fractured eye socket after being hit by Tarek Elrich’s elbow in the second half, before Cunningham was rushed to hospital in the dying moments with a suspected broken foot.
"It's one of those days where when things go wrong, they go wrong properly," Merrick said.
"It's a hazard of the job I guess.
"It looks like we've got a fractured eye socket for Reece Caira and I'm not sure about Kenny, it may be a broken foot.
"If it's a fractured eye socket (for Caira) with two months to go, he'd be struggling to come back from it (this season), I'd say."
Notwithstanding the two casualties and the fact the Phoenix finished the match with nine players on the park, Merrick acknowledged his side, buoyant after last week's 4-1 comeback win away to the Central Coast Mariners, was destroyed by the Reds.
"I don't think we have any excuses for a poor performance," he said.
"I know we finished with nine players but when it was 11 v 11, we were well beaten by Adelaide.
"They kept the ball in midfield really well, they created numerous chances, and (midfield pair) Vince (Lia) and Manny (Muscat) were outnumbered 3 on 2, in the middle of the park.
"Adelaide came out and they were buzzing - every 50-50 they won.
"They were first to the ball, we were always chasing, they kept possession really well and we just couldn't get into the rhythm of the game at all."
In fact, Wellington have battled for rhythm and continuity in their defensive stocks for most of the season, a trend indicated by the fact they have leaked the most goals of any side.
With the likes of Spanish-born left-back Albert Riera (groin) and right-back Louis Fenton (shoulder) sidelined plus Caira's serious injury, Merrick has battled to piece together something resembling a plausible back third.
"It's been a season of patching up full back positions," Merrick said.
"Playing a centre-back at right-back, changing the left-back because Manny (Muscat) had to move into midfield, we lost Albert Reira ... it's just been a season of patching up, changing and losing players to the national team."
