Wilgar (#49) was doing his job and playing contain. If he had crashed down on that play and the RB reversed field, there is nothing but green grass in front of him. Wilgar probably could have been positioned better, it’s hard to tell from that video angle what kind of angle he had on the ball carrier - but he certainly didn’t look casual, relaxed, or like he had no motor - he was simply trying to do his job.
The great defenses that you referenced relied on individual players to be assignment sound and disciplined. I think this defense is both of those things. They have done enough for us to be 2-0 right now but the offense continues to struggle.