"We just played a little dumb and that carried on into the second-half and it was only in that last 10 minutes when we had nothing to lose that we really found the way we wanted to play.
"In the second-half we made too many errors and even when we finished our sets they were poor finishes and so we didn't really mount any pressure until those last 10 minutes.
"(There was) Lots of effort but it wasn't a great performance."
The result followed last week's golden point loss to Manly in Perth and the round 16 loss at Cronulla, in which field goals cost the Warriors victory.
In each of those matches the Warriors displayed a tenacity that was glaringly absent throughout the opening 12 rounds and Saturday's defeat was the first time in seven games they conceded more than three tries and leaked more than 20 points.
Despite showing plenty of attacking intent, the Warriors have struggled to score tries and have been held out for extended periods by both the Raiders and Sea Eagles.
Against Manly, the Warriors failed to cross the chalk in 55 minutes after Bunty Afoa ran in his second try on the half-hour mark. That drought was repeated against Canberra, with the Warriors going scoreless for 53 minutes between Manu Vatuvei's 150th NRL try in the 17th minute and Thomas Leuluai darting over for the first of two four-pointers in the 70th minute.
A harsh obstruction call saw them denied the opening try to David Fusitu'a in the 12th minute, but a lack of composure and accuracy, with several passes going above or behind the mark, ruined other promising attacking scenarios.
Despite his side's improved effort and resilience captain Ryan Hoffman warned they needed to be better if they are to book a spot in the top eight.
"We didn't play too smart," said Hoffman. "We've met every challenge, especially over the last two weeks, head-on and we've come close.
"Effort's great and competing's great but we need to start getting the two points."
The injection of Tui Lolohea 13 minutes into the second-half boosted the Warriors and with Manu Vatuvei battling a knee injury and in doubt for Saturday's clash against Penrith, the 21-year-old could reclaim a starting spot on the flank.
Forwards Bodene Thompson (ankle) and Albert Vete (hamstring) are also both a chance of returning for the first of four home games at Mt Smart Stadium in the last six rounds.
"We're still confident," said McFadden. "As long as we put in that effort and we can tidy up a few areas there's no reason why we can't finish strong."