West Ham strikers Diafra Sakho and Enner Valencia have provided intensity without the ball as well as scoring goals

“It’s not just the back four. We defend as a team.” Sometimes you get the impression that players are on auto-pilot when doing the post-match interview but when James Collins made the point after West Ham’s 2-1 win over Manchester City on Saturday, you sensed he meant it.

The impact of summer signings Diafra Sakho and Enner Valencia has been stunning. The identity of last season’s strike options - Andy Carroll and Carlton Cole - summed up the approach. But the new arrivals have shown that there are other ways of winning the ball high up the pitch.

The intensity with which the two have led the line has been quite a sight. In the 1054 minutes that Sakho and Valencia have played so far, they have made 17 tackles and 10 interceptions between them. Carroll’s 1093 minutes last season brought just eight tackles and one interception. The old line about defenders ‘knowing they’ve been in a game’ has seldom seemed so appropriate.

Of course, the main difference has been the goals. Carroll got just two last season. Sakho has six already, including the winner against City, becoming the first player to score in his first six Premier League starts. Valencia has two of his own and got the assist for Morgan Amalfitano’s opener on Saturday. Hammers favourite Tony Cottee believes he might be the better signing in the long term.

Improvement certainly seems likely. Both men are 24 and are remarkably hungry. Valencia signed from Mexican club Pachuca while Sakho had not even featured in the French top flight when he joined from Metz. As a result, they’ve approached the challenge with real enthusiasm. “I'm going to give it my all, going flat out on the pitch and I think the fans will appreciate that,” said Sakho upon his arrival.

That’s proven to be an understatement. There was a little uncertainty regarding who was the catalyst behind West Ham’s recruitment drive in the summer, with reports that manager Sam Allardyce was not too keen on the club signing Mauro Zarate having remembered his spell at Birmingham. But Sakho and Valencia certainly adhere to Allardyce’s ethos of defending from the front.

“Diafra has so much energy and desire,” said Allardyce recently and the statistics back that up. Indeed, Sakho has made the most interceptions of any Premier League striker so far this season. He’s in the top 10 for tackles too – such as the crucial one he made when one-on-one with Yaya Toure in his own box at the weekend.

Against the champions, the Opta data shows that Sakho was involved in 29 duels. Nobody else contested more than 16 and that man was Valencia. They compete for the ball in the final third. West Ham’s attacking coach Teddy Sheringham said of Sakho last week: “He is up there in the right or left wing position, up the middle and then tracking back to the full-back positions.

“He pops up everywhere doing something for the team, which makes him invaluable. When you look up front and see two boys working their socks off to close people down and stop their full-backs getting out, then it's invaluable for the team and you get a boost from that.”

Sheringham makes the point that it is both of them and Valencia did play a crucial role in that against City. He won possession as many times as he lost it, particularly rare for a forward player. In fact, he was the only starter on either team to achieve that. By comparison, Sergio Aguero lost the ball four times as often as he won it; Edin Dzeko