GP
Go Texans!
I don't know why not. They didn't implement an entirely different system ("Frank Bush's System"). They edited Smith's system down to the stuff that worked and told him not to deviate from that subset of his defense. In short we saw Richard Smith's defense with all the looney bits removed. What remained was still his and will probably bear some resemblance to whatever Frank Bush implements which is fine. It worked.
They always talk about simplifying things to make them faster and to get players moving instead of standing there trying to work everything out. They pared Smith's defense down to only that (arguably making it so generic it was hardly attributable to anyone) and it worked... at least better than what he'd been doing. Compared to the full package "Richard Smith Simplified" looked like we'd suddenly become the 85' Bears.
Frank Bush's system will have to be a damn sight better than that for him to be considered a successful hire.
I can't envision a grown man actually allowing someone to hand him a sheet of paper that says "You can do a, b, c but not x, y, z."
That's the lowest of lows. If you're Richard Smith and you get told you can and cannot do certain things, how do you smile and eat that like it's delicious? Heck, if he WAS calling his own defense but with certain boundaries...and he sees the effects of it, wouldn't that be like a major wake-up call of some sorts?
You have to be a special sort of person to keep getting things wrong, being shown how to do something right, and yet still revert to your wrong ways at the end of the day. Maybe it's an overboard issue of pride or something.
I personally could not continue running the show if someone behind the scenes hands me a sheet of paper and says "This is what you do, got it?" (1) I'm wasting my time. (2) I'm wasting other people's time, and (3) There's something else I need to go and do, something I can put my hands to and do an OK job at.
Maybe I won't set the world on fire when I move on to something else, but at least I won't wake up and live a lie. If Richard Smith was running his defense, but couldn't see the faults of certain parts of it nor could he see the successful parts of it and that he needs to do more of the successful things...then I say "Wow, how in the heck did he get a job with the Texans in the first place?"
And if people think the Texans didn't 'try' hard enough by naming Bush d-coord, then all I can say is they must have drawn Richard's name out of a hat during a golf game three years ago or something.