Tyron Smith may be 20 years old, but he's a plug and play starter. Smith is the best offensive tackle in this class, and it isn't even close. The NFL knows about his play at USC and his huge upside. Smith is a blue chip player and an excellent value at 9, and he would be the cornerstone of Dallas' offensive line for at least 12 years. He will not get past Dallas, Washington, Minnesota, and Detroit. Cleveland (at number 6) likes him, or they wouldn't be looking him over so close. That should tell you something about Smith, because they already have Joe Thomas.
NFL teams view Smith's future on the left side for a reason, and if the Cowboys are fortunate enough to get their hands on him, it's possible that they could play him at LT right off the bat. Although, Free gives them flexibility to start him out on the right side. Smith has all the tools to be an elite NFL OT (LT or RT), and Doug Free is a serviceable LT and will most likely never be an elite LT.
Charlie Casserly has stated that he thinks Smith can play LT and compared him to D'Brickashaw Ferguson (who played in the 285 range at Virginia). Casserly stated that Smith passed his LT footwork and the push/pull strength drill with "flying colors". On that same segment (Path to the Draft), Brooks back pedals from his "RT" stance and aligns his opinion with the vast majority opinion about Smith's LT ability.
At 285, Smith's length, balance (ability to bend and play with a wide base or sink), and agility enabled him to display more power than Solder or Castonzo or Sherrod. Add this to the fact that (again) Carimi's weight at Wisconsin was listed at 327, and his weight at the combine was 314. Is Carimi going to gain more athletic ability to play LT in the NFL? His future highly most likely is going to be on the right side in the NFL. That is where he is being projected. Carimi's calling card isn't athleticism to start with. It's power, and if he loses some pop, he could get bull rushed and pushed around in the NFL, due to his vulnerability against NFL speed on the edge.
The Cowboys have won 1 playoff game since 1996, missed the playoffs twice in the last 2 years (Romo hurt both missed years due to leaky pass protection), are drafting in the top 10, they have a serviceable Doug Free (4th round pick) at LT, the worst RT (Colombo) in the NFL who already makes significant money, and an old, deteriorated interior of the offensive line. There really is no excuse for not wanting to take a blue chip, cornerstone offensive linemen like Tyron Smith, especially when he's staring you in the face at number 9.
I think that Tyron Smith is Jason Garrett's number 1 prize for a couple of reasons. First, he has to know that the offensive line is literally going to completely collapse like a house of cards next year, if something drastic isn't done. Second, Smith is exactly the type of player that Garrett covets, not only for his offensive line but for his football team. Jason Garrett knows that winning starts up front, and he has to be very concerned (especially after 2010) about his great skill players on offense, not being put in the best positions possible to succeed, due to very poor offensive line play. If Peterson goes off the board, and Garrett is able to nab Smith at 9, I don't think Garrett is going to shed one tear.