I thought the Giants O-line was terrible (although missed the third quarter), with Jerry not being able to pick up stunts and Hart seemingly getting beaten with the edge rush on a consistent basis. I didn't think Flowers did that badly. Well, PFF says that the line didn't do badly at all.
http://giantswire.usatoday.com/2017/09/12/new-york-giants-offensive-line-not-dominated-loss-pff/
In their Giants correspondence points e-mail, PFF shared the following:
RG John Jerry allowed two sacks and two hurries on 45 pass blocking attempts (73.4 overall), but it was LT Ereck Flowers who earned the lowest overall grade among offensive lineman (53.4 – 39th among tackles on the week). Flowers allowed a sack and a hurry. RT Bobby Hart allowed three pressures, but still finished with a 77.5 overall grade – ranked 16th among tackles on the week.
Weston Richburg (78.8 – fourth among centers) and Justin Pugh (78.1 – 15th among guards) were great as usual for the Giants offensive line, neither surrendered a pressure on 45 pass blocking attempts and performed well in the run game.
The Giants did not get dominated up front. Richburg, Pugh, Jerry, and Hart all had run block grades above 76.4 – running the ball just 12 times total, Giants RBs failed to force a missed tackle. However, they were not given much of an opportunity with so few attempts.