The best way for the Giants to help struggling quarterback Eli Manning is with a little more Brandon Jacobs circa last Thursday night in Chicago. Sure Jacobs’ 106 rushing yards on 22 carries against the Bears came in a loss but it was the most positive thing to come out of that game for the Giants considering it was Jacobs’ largest rushing output since Dec. 13 2010 and the Giants are desperate for a strong running game. “It felt normal’’ Jacobs said. “I felt good out there. It’s nothing that I haven’t done before.’’ Yes but it was nothing he had done in a while. His last 100-yard rushing game came in 2011. The question now is whether Jacobs can duplicate his Thursday night performance when the Giants take on the Vikings Monday night. The Giants are ranked 30th in the NFL in rushing offense and their lead back David Wilson may not play against this season because of a neck injury. So the Giants are in desperate need of another reminiscent performance from Jacobs who has always been an emotional spark to their offense. “He ran hard and he was spirited’’ Giants coach Tom Coughlin said Thursday. “He was physical he gave our team a nice lift — defense offense special teams. I hope he can keep doing it.’’ The way Jacobs carries himself and moves the pile when he’s running well energizes his teammates. Jacobs too is a vocal leader whose leadership takes on a much more significant role the more he contributes on the field. “He’s a voice in here’’ Giants receiver Victor Cruz said. “That’s a voice that I missed when he left [after the 2011 season]. He was one of the most dominant voices I heard when I first came here always making his presence felt. All you can do is rally behind a guy like that. I love the guy to death.