I get a kick out of people on this message board who act like they know the "system" and conclude that Romo wouldn't succeed in the offense.
To answer your question, nobody knows how Romo would do in this system.
However, I think Romo needs better coaching. My friend is a Cowboys fan, so we watch every game. I pretty much know the Cowboys like I know the Pats and I'm not a fan of Garrett or Phillips. On the other hand, at least Garrett is finally seeing the light and doing his best to utilize the biggest strengths on the team, the RB's. Also, I hated the Roy Williams trade then, and I still hate it now. The 'Boys could've easily used that pick on a young WR and signed a FA WR instead of Roy Williams.
In addition, I find it funny when people say an undrafted free agent (Romo), who has been the starting QB for the Dallas Cowboys since 2006 is an underachiever.
By the way people put him under the microscope, you'd think this guy was a 1st overall pick in the draft.
In the end, it's a pretty much lose-lose situation for Wade Phillips. If the Cowboys make the playoffs but fail to win a game, I can see him getting canned. If the Cowboys miss the playoffs, I'm pretty sure Phillips gets canned. If this happens, I can see Shanahan making his return with the Cowboys.