Collins felt he was never in Villa manager Paul Lambert's plans in preseason.
"As soon as West Ham were interested, that was it," Collins told the Daily Mail. "I got the vibe, and I think a couple of other players got the vibe that our time at Villa was done.
"We didn't have the best couple of years. They were looking for a change and I was looking for a change to kick on again and coming to West Ham was great."