Which Doug Free shows up will be key

IRVING, Texas -- Maybe more than any other player on the roster, the Dallas Cowboys need Doug Free to be the best version of himself, to borrow one of head coach Jason Garrett's coachspeak catchphrases.

That version is a good tackle and veteran leader on an offensive line that is expected to be one of the league's best. The other version of Free is a weak link.

Which Free will the Cowboys get this season? The answer should play a major part in determining the potency of a Dallas offense that has the potential to be as explosive as any in the NFC.

The problem: Free might be the most unpredictable player on the team.

For whatever reason, Free's four seasons as a full-time starter have been a roller coaster. He was very good in two of them and terrible in the other two.

Just look at where Free ranked among offensive tackles in Pro Football Focus' grading system the last four seasons: tied for fifth in 2010, 51st in 2011, 68th in 2012 and 20th in 2013.

Those looking for reasons to be optimistic can take some comfort in the fact that Free has been at his best when he had major financial motivation. He was playing for a contract in 2010, when he had the best season of his career and cashed in with a four-year, $32 million deal. Last season, after Free accepted a pay cut that slashed his salary in half over the option of being released, Free had a bounce-back campaign, which was probably necessary to keep his roster spot with this year's $3.5 million not being guaranteed.

Now, Free finds himself playing for a contract again with the right tackle's deal voiding after this season.

Another factor, which the Cowboys consider much more important, is Free's comfort level playing for offensive line coach Bill Callahan. This will be Free's third season under Callahan, and the Cowboys believe he benefitted last year from a better understanding of the techniques Callahan coaches.

The bad news is that the last live glimpse we got of Free wasn't exactly encouraging. He gave up two sacks in a half playing against Pro Bowl pass-rusher Cameron Wake in the preseason loss to the Miami Dolphins, when the starting offensive line as a whole was a disappointment.

Garrett noted that Free's performance outside of the two sacks allowed wasn't bad, but subjecting Tony Romo to that sort of punishment is never acceptable.

"Any time you give up a sack, it's not something you want to do," Free said. "You want to play all year without giving up a sack. At times, it happens, but you try the best you can to not give up a sack. He's a good player, but it's something you've got to shut down."

Added Garrett: "You certainly have to learn and grow from that situation."

If Free performs as well as he did last season, he'll fly under the radar, which is fine with him. If he turns back into the 2011 and 2012 version, he'll get plenty of attention as one of the primary reasons as high-powered offense is underachieving.