Stoke 0-1 West HamSoccer Saturday analysisDiego Tristan's fine first-half free-kick won the game for Gianfranco Zola's side as the Hammers kept their quest for European football alive.
Merson felt they made the game safe thanks to their ability to retain possession - and also thanks to the safe hands of their England goalkeeper.
"I was impressed very much by Robert Green," Merson told Soccer Saturday.
"He didn't have a lot to do, but when he came out and took the ball I thought he was absolutely brilliant.
"Also, West Ham did what a lot of teams haven't done at the Britannia this season by keeping the ball when they got it.
"Even when Stoke closed them down they kept on keeping it and keeping it and I was impressed with them.
"They just kept it for fun and that was it really."
Merson hailed the wonder strike that settled the game, but was less sure about whether West Ham should retain the services of the goalscorer next year.
However, he felt Tristan would make a marvellous substitute, as long as his wage demands are not too high.
He said: "The goal was world class from Tristan and was worthy of winning any football match at all.
"It's difficult to say whether he should get a new contract because they've got a few forwards, some of them are injured at the moment like Carlton Cole, so I don't know.
"He scored against Villa the other week and he went through one-on-one again with the keeper and could have finished the game, but it was a bad finish.
"When you've got class like that it would be nice to bring it on. It depends how much money they're on a week.
"If he's not taking millions or thousands I'd take him on a free transfer. If you've got somebody who can do what he did today it's priceless."
As for Stoke, Merson detected an element in tiredness that you don't often see in their play, but insists they are already safe from relegation.
"They've not taken their foot off, but they are getting a bit tired now," he added.
"For me they're completely safe, they're not going down, but it was hard work for them today.
"They always their set plays and the long throw-on, but bar that it wasn't the Stoke that you usually see."
"West Ham kept the ball too easily compared to other teams at the Britannia when they are all over you like a rash."