EAST RUTHERFORD, N.J. – Mike Tomlin was philosophical and at the same time analytical in the wake of the first big play of the preseason surrendered by the Steelers' defense.

"We're going to have big runs that break out every now and then," Tomlin offered after running back Rashad Jennings' 73-yard touchdown run opened the scoring for the home team in what became a 20-16 Giants' victory in the Steelers' preseason opener on Saturday night at MetLife Stadium.

"Obviously, it was a gap-integrity issue in the core but that's less of a concern. I'm more concerned about, when those things do occur, that we do a good job of trying to minimize the explosion play and make it an 8-, 10-, 12-yard gain, not 78.

"We got to get it on the ground in the secondary."

Jennings took a handoff on the Giants' fourth offensive snap and went up the gut through the gap between left guard Geoff Schwartz and center J.D. Walton and ran almost untouched into the end zone (diving safety Will Allen got a hand on Jennings at the New York 41-yard line, 14 yards into the jaunt).

The Steelers' starting nickel defense was on the field for the start of the second series of the preseason, with the exception of inside linebacker Sean Spence (filling in for Ryan Shazier, who did not dress) and Allen (filling in for Troy Polamalu, who was held out of the game by Tomlin).

"I'm fully responsible," defensive end Cam Heyward said. "I messed up for this team. It won't happen again."

Inside linebacker Lawrence Timmons also claimed responsibility.

"I'm supposed to be in the A-gap right there," Timmons said. "I got to make that play, me being the middle linebacker."

Heyward was moved from his gap laterally by offensive tackle Charles Brown. Timmons was held by pulling guard Brandon Mosley. And neither Allen nor free safety Mike Mitchell – both  unblocked on the play – could cut off Jennings' path to the end zone.

"The secondary has to make a tackle," Allen said. "We didn't. I didn't. You don't want it to happen, but it's preseason. We have a chance to correct it. We have to eliminate it next week."

BACK TO BACK TO BACK: The early distribution of labor at running back shed some light, perhaps, on how the Steelers intend to keep Le'Veon Bell, LeGarrette Blount and Dri Archer involved this season.

Bell started at running back, was replaced by Blount when the Steelers entered the red zone and then replaced Blount on third down in the red zone on the Steelers' opening drive. Archer entered initially as a slot receiver.

The first four plays were runs of 9 and 8 yards by Bell, a 46-yard screen to Archer and a 5-yard run by Blount.

"It was crazy how they were spreading the ball around with the three backs," Bell said. "I'm excited to see what this offense can do."

ZERO TOLERANCE: The NFL has vowed to keep a close eye on illegal contact, illegal use of hands, hands to the face and offensive pass interference this season, and has made that intention clear via a video shown to players and coaches in training camps.

The Steelers were the beneficiaries of a defensive holding call against linebacker Mark Herzlich (on an incomplete pass to tight end Heath Miller), an illegal use of hands call against defensive end Jason Pierre-Paul (on a run by running back Tauren Poole that lost 1 yard), a pass interference penalty against cornerback Jayron Hosley (on an incomplete pass to wide receiver Martavis Bryant), and on a second pass interference against Hosley (this one on a long pass intended for Bryant).

The Steelers also declined an illegal contact penalty against cornerback Prince Amukamara on a 17-yard hookup between quarterback Bruce Gradkowski and wide receiver Antonio Brown.

All of that happened in the first two-plus quarters.

"It's going to be called pretty tight, at least during the preseason and maybe even on into the regular season," Miller said. "As long as they don't call me for pushing off, I'll take it."

NOT GOOD ENOUGH: Tomlin had said he wanted his team to play hard, fast and with urgency in the preseason opener.

He'll be looking for more of the same against Buffalo than his Steelers delivered in MetLife Stadium.

"I'm less concerned about style points," he said. "Tomlin said. "I'm more concerned about the bottom line. My emphasis in that regard was geared towards wining. So even if it was above the line it's going to have to be better."