"Consistently they hit us on the break," he told Sky Sports. "It was obvious and we still kept getting caught.
"It was very naive from our point of view. We've got to do something about it. We've got to look at things."
Coppell knew a result against West Ham could have changed the slant on their season and is now worried about their progress to date.
"The alarm bells are clanging on my brain," he continued. "We can do something about it for next time.
"If we could have got a result today, people would have said it was a strong start. Today was a huge game for us.
"On the back of the result and performance we look upon it as a poor start."
West Ham boss Alan Curbishley was a much happier manager.
'Today has shown that I've got a decent squad," he said. "And although a few of my injured players are missing, others have taken their chances and proved to me that they can come in and step up to the plate. Compared to last season, a totally different side turned up against Reading and it was a great result for us.'