"West Ham look transformed at the moment," according to ex-Hammers winger Matt Jarvis.
The 39-year-old was speaking to BBC Radio 5 Live Breakfast following West Ham's 1-1 home draw with Manchester United.
West Ham have picked up 10 points in their last five games, after 14 points in their opening 21 games.
"They look an attacking threat and solid at the back. It's been a good period of time for West Ham," said Jarvis.
"It [the belief] wasn't [there a few weeks]. It's there now. You look at the performances and atmosphere. A really great response."
Speaking about forward Crysencio Summerville, Jarvis said: "He's been outstanding. He was out for a long time with injuries and now he's in such good form. He's electric when he gets the ball. He's working back like everyone else.
"Taty [Castellanos] up front is running all day long. He's making sure the opposition defence don't have enough time on the ball to do what they want.
"Now they're a squad who are together. The crowd, the atmosphere last night was a massive difference to what it has been."
