Barkevious Mingo’s quickness and potential were evident to many Thursday as he pressured St. Louis Rams quarterbacks and registered a special team’s tackle.

But that’s not what most impressed the discerning eyes of veteran D’Qwell Jackson. The Browns inside linebacker saw a rookie whose energy level didn’t dip after the adrenaline from his first few NFL series evaporated into the humid evening air.

“He showed a tremendous amount of conditioning for (his) first game” Jackson said. “Usually it jumps up on you. Everyone remembers that first preseason game and you take a couple of deep breaths and it’s like ‘OK this is the real deal.’ But I watched him every play and he’s got a knack for getting after that quarterback. He has a motor and that’s something you can’t teach.”

The Browns edge rusher selected No. 6 overall in the draft gave fans a glimpse of what they might come to expect at FirstEnergy Stadium. He recorded two quarterback hits and had a second-quarter sack nullified because coach Rob Chudzinski accepted a 10-yard tripping penalty that Mingo drew on Rams left tackle Joe Barksdale.

The outside linebacker spun free from Barksdale and barely touched backup quarterback Austin Davis who dropped to the turf on contact.

Mingo looked to the sideline and playfully waived his arms in hopes Chudzinski might decline the infraction and credit him with a 6-yard sack.

“I thought he was really explosive” outside linebacker Paul Kruger said. “He’s just got to refine a few things and he’s right there. He’s an extremely talented guy and he knows the defense. For him it’s going to be good progression really quick.”

Playing in front of his mother several siblings and his girlfriend the West Monroe La. native enjoyed his NFL debut. He worked primarily with the second unit but on the game’s first defensive series coordinator Ray Horton deployed four edge rushers -- Mingo Kruger Jabaal Sheard and Quentin Groves -- for one play. Despite getting serious pressure Rams starter Sam Bradford completed a 20-yard pass.