The visitors had less than a third of the ball through the first 12 minutes of the game but had only conceded one try and when the tide began to turn they quickly levelled the scores with a superb four-pointer to Bevan French.
But as soon as they had returned to level terms with the Raiders the Eels dropped their guard and the resulting three tries in the space of seven minutes that they conceded gave them an assignment that would prove to be too challenging.
After trailing 22-6 at half-time Parramatta scored the first two tries of the second half as their share of possession evened out and got back to within four points heading into the final 20 minutes but were unable to find the go-ahead play.
"I thought we played well for 60 minutes; that 20-minute period killed us," Arthur said of the period just prior to half-time.
"From there I think they had four or five sets in a row and we just lacked a bit of urgency on a couple of loose balls.
"That's the frustrating thing, we can't play good in patches. We've done that against Cronulla, we've done that against Gold Coast; we've got to play for 80 minutes if we want to be a chance.
"It's hard to win an NRL game."
Facing a 16-point deficit against a Raiders team threatening to run riot at home, Arthur commended the commitment of his players and their response after he issued them a challenge at half-time.
"I'd be devastated if I was coming in here and saying that we rolled over and we didn't play tough and they're not trying – because they're trying hard," Arthur said, the Eels still winless in Canberra since 2006.
"Sometimes you can try too hard to make things happen. We've just got to remain patient and things will come for us.
"They're a good team. Four weeks ago they were one of the premiership favourites. We were pleased that we could come out and start the second half the way we did.
"I challenged the boys at half-time and they responded really well.
"I think we won the second half but you've got to win every half and you've got to be in the game for the 80 minutes.
"Lack of concentration and a few areas for a 15-minute period really hurt us."