In a topsy-turvy game the Hammers took the lead before being blown away by the Royals.
"I never thought before, based on where we were and how we have done, that we would ever concede four goals here,” Sam told the official site.
“But we have and that's why we have lost; our defensive unit today didn't function as normal and that was a big blow to us which ultimately cost us after such a good start to the game.”
The defeat leaves the Hammers four points behind Reading and Southampton in the automatic promotion spots.