I understand where you are coming from, and especially thought Gordon, in particular, at times looked like he was trying to "look" too cool for school and to appear ultra-casual and calm even when not warranted.
That said, it's hard to knock the offense for much at all. Gordon was off-target in a couple of key late possessions, with it looking a bit too much like 2017 Falk to me ... stand back there and throw an uncatchable ball to a blanketed receiver, when (I have to go back and watch) it seemed like him threatening to take off might have opened some things up. The failure to score there hurt.
Subject to that, one man's "casual lack of urgency" is another man's "staying composed." If the offense had started to look like it was freaking out, then the complaint about them (and Leach) would be that they were freaking out and shit the bed. I think they were trying to just do their job, which was all they had to do. They had the ball with the lead and two and a half minutes left. All they had to do was get a first down and the game was pretty much over, and it definitely was over if they got two. Winston's fumble blew that.