"We have some players who still don't realise how tough this league is. You have to maintain your standards for every game. If you don't, you get punished."
The Phoenix looked off the pace from the start against a Perth team on a five-game unbeaten run. Conceding in the second minute was an awful start, as Tom Doyle was caught out and Glen Moss was uncharacteristically hesitant at shutting down the angle for the cross.
But that's going to happen, especially with Doyle who is learning his trade but worth persevering with.
The concern was the lack of response.
The team certainly missed Michael McGlinchey's creative edge - the All White flew back to New Zealand for the birth of his second child, who arrived on Friday - but there should be enough quality without him. But the visitors struggled to make any impression in the first half, easily kept at bay by the Perth defence as too often passes went astray.
"We need to create more chances," Merrick said. "We are struggling to create opportunities and that puts pressure on the whole team."
Nathan Burns had his quietest match of the year, Jeremy Brockie failed to make an impression and even Albert Riera had an off night. The ever-improving Roy Krishna provided a bright spot - his accomplished spot-kick means the Phoenix have finally found a penalty taker - but the Fijian also missed a good opportunity in the 58th minute before Perth doubled their lead two minutes later from a similar scenario.
Merrick says he is "not concerned" with the defence and midfield, and will focus this week on the work in the front third of the field.
The Phoenix remain in the top six but will need a vastly improved effort next Sunday against Melbourne City.
They also need to regain some momentum ahead of their annual game at Eden Park against the Central Coast Mariners on December 13.