The visitors were 3-0 up at the break after dominating the opening period and, although Adam Le Fondre and Jimmy Kebe offered a glimmer of hope, there was to be no miraculous recovery.
"In the first half they played very well and we didn't get close to them. We changed shape in the second half and got better, got two goals but the fifth killed the game," said McDermott.
"We could have got tighter in the first half. Their three midfield players were excellent, but the second half response was good from our point of view.
"That game won't shape our season. We've got a lot of home games to come which will be defining for us.
"We have to do better than we've done. We play Manchester City away, then we've got Swansea and West Ham at home, which we're looking forward to.
"But we can't look too far ahead, we've just got to keep going. We're doing everything in our power to make sure we're in this league next season.
"It's a strong possibility that we can get players in and we'll try to do that.
"We'll see what January brings. We all know it's a tough window but we've been planning for some time now and that's what we'll be looking to try and do."
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