Coming off a four-match winning streak, the Victory were thrashed by the New Zealanders at Westpac Stadium - the 2-0 result actually flattering the visitors.
Merrick said his players were lethargic but offered no more as to why his team was brushed aside by a club sitting outside the top six.
''It was a very poor, lethargic performance,'' Merrick said. ''We were mentally tired and just not up for it. One team looked up for it and they were full of running.
"We had too many players down on performance and we were beaten by a better team.
''We got absolutely nothing in midfield. We really struggled to hold onto the ball.''
The Victory will now prepare for a big clash with second-placed Adelaide United on Sunday and Merrick was eyeing a massive improvement from his players.
"We've got good players and we always play well against Adelaide,'' he added.
''Any defeat is tough, but it's all about how you respond. We'll pick ourselves up quickly from this.''