In the play you displayed, I would have to say the NT is pretty weak. In real football, the NT is almost NEVER single-teamed. Because of this, the G's were left one on one with the ILB's who are supposed to be able to make these plays. The FB comes into the hole where he chips the ILB, who is one on one with a G, and it's off to the races.
I am not sure if this is just a flawed sim or if it's the players, to be honest, but this is like an illustration of he way a 3-4 worked in the early 80's before the super beefy NT's were around, and before the DE's in a 3-4 were more like converted DT's.
Well, I used the 3-4 for most all the seasons I have owned my first Casual team. We ditched it late in the Season. I've found not many people really know how to build an NT and "The Rock" NT is one of the largest Keys to a 3-4.
The switch is almost complete for us.. just one more player to add in DT position but it will, and did work better for my team.