Personally, I don't think it had anything to do with "experience".
I think it had more to do with the arrival of Miles Austin.
Tony Romo finally had a playmaker in the passing game that was hungry, humble and most importantly, won't wine when he doesn't have a lot of balls thrown to him in a game. Every Quarterback in the NFL would love to have someone at receiver with those intangibles.
The Kansas City games is one of the most important games in recent memories and I will even say it was more important then the Eagles game last night.
Besides, Tony Romo was never the main problem with this team anyway. Anyone who thought he was the main problem probably had an agenda or wasn't watching the games.
At some point, you will have to start putting Tony Romo in the MVP discussion.