FOLLOWING the 21-point loss to St Kilda on Saturday night, West Coast coach John Worsfold admitted he "could not put his finger on it" as to why his side gave the Saints a six goal lead in the first quarter.

The Eagles were completely blown away by the rampant Saints in the first quarter, with St Kilda opening up a 43-point lead early in the second term before West Coast fought back to hit the front late in the third term.

But the Eagles were left to rue a disappointing first quarter and costly mistakes and turnovers in their defensive half late in the match as they let slip the chance to occupy a position in the top four with their fourth consecutive loss to the Saints.

"We couldn't get our hands on the footy. They ran rampant and used the ball well, kept possession in the first quarter. But we addressed a few things there and fought back pretty well after that," Worsfold said.

"They just found loose men too often. Our run in that first quarter wasn't as hard as it has been.

"The margin blew out with a couple of poor mistakes [late in the match]. If we didn't make those mistakes there might have been another chance to go down and score at the other end."

The loss means the Eagles are still two points shy of Carlton, who currently occupy fourth position.

Worsfold admitted his side was made to pay for lapses in concentration throughout the match as the Saints ended the Eagles' five match winning streak that had claimed the big scalps of Geelong and Carlton.

"It's a four-quarter game. One team dominated for certain periods, the other got on top for other periods. In the end the better team that does it for that bit longer and that bit better wins the game," he said.

"In the last quarter it was a pretty even game and it was up for grabs. A couple of mistakes cost us late."

But despite the loss, Worsfold still found plenty of positives, reiterating his side is still on the right track.

"It's disappointing to lose the game but I was proud of the way the players responded to a good team up and going that dominated the game in the first quarter," he said.

"Our team in the past might have struggled to get back into that game and I thought it was an outstanding effort [to get back into the match].

"It shows how far this group has come I think, with the way we reacted."

The development of the Eagles youngsters continues to impress Worsfold, with Andrew Gaff shining, finishing the match with 21 disposals and two goals in an impressive performance.

"He showed a lot of good signs. Overall we are pleased with what he gave us today," Worsfold said.

Next week's derby against Fremantle on Sunday is crucial for the Eagles, with Worsfold admitting he was unsure as to whether key midfielder Daniel Kerr will return for the clash after missing with a hip and glute complaint.