Fair enough.
But consider this: Parnell would most likely be cheaper to resign that Free and is younger and has more upside.
This is also going be his 3rd ever start at tackle in LIFE. That means if he is your future, then the rest of the games this year are also invaluable experience that will make him better next year and he'll be missing out on if you just install Free back.
To me, the ultimate solution would be to just rotate them in and out like we did at the end of 2012. It didn't hurt the line chemistry that much then and I doubt it does now.
All things being equal, I prefer that Parnell remain the starter because he is younger than Free and could be a longer-term solution for this line. I don't know if he's necessarily going to come cheaper than Free, because I think someone will offer him a starting job no matter what happens here ... unless he stinks in tonight's game then is replaced by Free in the next game.
I do believe he could end up being better than Free because the only thing Free has going for him in comparison is a better understanding of how to play the position, which allows him to win some technical battles that Parnell doesn't always put himself in position to win. That would probably change with more starting experience.
I don't mind the rotation scenario, but I also don't believe Dallas sees that as ideal. The only reason the Cowboys did it in the first place was because Free was playing so poorly ... which was primarily caused by technical issues that he's mostly cleaned up. (Free isn't a player who can afford technical issues while Parnell has the physicality to better overcome his.)
So, I don't see Parnell remaining the starter or rotating in ... unless Free struggles. Because of that, Dallas probably will re-sign Free and Parnell will head for greener pastures. That's not ideal to me, but it isn't like Free can't play out a four-year contract because that would mean he'd be only 34 his final year and he didn't get much playing time his first few years (this being only his sixth season as a full-time starter).
If Free keeps playing the way that he has last year and this year, we'll probably end up letting the player with the higher ceiling go, but I don't think that necessarily means we'll regret the choice.