The number two says a strong squad and several other factors have helped them to third in the table.
The Hammers continued their impressive start to the season with a 2-1 win over the struggling champions on Saturday afternoon, with a goal from Andy Carroll securing a win that moved them up to third in the table.
The Blues were the latest of the big four to be beaten by Slaven Bilic’s side this season, with Arsenal and Manchester City having also been seen off, and Jurcevic says this victory was like a dream.
“At this moment we are really happy,” he told whufc.com.
“It must be like a dream because we won against a really big club. Our performance today was really perfect. From the first minute, all the team fought very well and were helped by our fantastic supporters.”
The assistant manager was also full of praise for the West Ham squad that he and Bilic have at their disposal.
Bilic was busy this summer as he brought in a number of new faces to reshape the unit he inherited from Sam Allardyce in his image.
All of those signings have settled quickly, with the likes of Manuel Lanzini and Dimitri Payet starring, while some of those already at the club have stepped up to impress their new manager.
And Jurcevic says that strength in depth, coupled with a great atmosphere, hard work and discipline has helped them to their current lofty position.
“We worked hard for the last three or four months and we have found a really good team,” he added.
“Not only the first eleven but also another seven, eight or nine who are ready to help our team. We have also a great atmosphere in the team, along with discipline and hard work and all together, these help us to be in this position.”