Six days before the defeat, Leeds had beaten Hull KR 50-0 at Wembley, but they lost 32-18 to the Saints at Headingley.
“You could say it was expected, but we have higher standards than that,” Achurch told the Yorkshire Evening Post.
“I wouldn’t say it was a comfortable win, but the Cup final didn’t take a lot out of us physically. It was more emotionally.
“Physically we were ready to play on Friday, but in the second half we dropped off a bit and that was probably the emotion of it all.
“St Helens are a good side and they wanted it a little bit more than us. You could tell in just about every tackle that they were up for it.