Has anyone compared the dno graphs vs reality?

In my short 300 mile life with my CTS, I have.

I haven't yet pushed near redline, maxing out at about 5k rpm, but knowing what the dyno graphs look like, I definitely notice the torque dips across the powerband.

Anybody an engine tuner or an engineer who can explain why power delivery is so non-linear?

I can only equate it to electronics, as all of the engines I've ever dynoed delivered linear gains throughout the powerband.