It was a “wow” moment on an otherwise dull night. Rashad Jennings took a handoff from Eli Manning and jolted the sleepy MetLife Stadium crowd awake. Big Blue’s new running back took a simple straight away handoff from Eli Manning, burst threw a canyon-sized hole up the middle and exploded to pay dirt, 73 yards later, showing off impressive breakaway speed, running away from the Steelers’ secondary. It was quite an introduction to Giants fans. “I actually put it on social media [before the game], this is the first time as a Giant I get to play in the stadium,” he said after Big Blue’s 20-16 preseason victory over the Steelers. “You only get one chance [to make] a first impression.” In what was otherwise a lost evening for the Giants’ first-team offense — Manning failed to complete a pass and was sacked once in four possessions — it was the lone highlight. After getting through the line untouched, the Steelers never had a shot at him, Jennings using his speed to get to the outside and find the end zone. “One-on-one battles in the open field, you got to win those,” said Jennings, who had an 80-yard touchdown Nov. 17 against the Texans. “It’s what I did and the rest was just a race. … I never had any doubt. I’m not a man of doubt. Plus, you got those big screens TV’s up there. You can see where they’re at.” The Giants spent the offseason bringing in one big-name free agent after another, luring cornerback Dominique Rodgers-Cromartie from Denver, linebacker Jameel McClain from Baltimore and offensive guard Geoff Schwartz from Kansas City.