The value of cornerback has changed as more teams go to wide-open passing attacks, and the Cowboys say they are comfortable with their top three of Brandon Carr, Mike Jenkins and No. 1 pick Morris Claiborne. “Cornerback is a premium position,” head coach Jason Garrett said after the Cowboys traded up aggressively for Claiborne. It appeared to be a shot across the bow of Jenkins, whose play has vacillated since being a No. 1 pick in 2008. He made the Pro Bowl in 2009 but struggled with consistency the past two seasons. Reports surfaced that the Cowboys would try to trade Jenkins during the draft but that the value they set was high. Jenkins is entering the final year of his rookie deal, and we hear the team hasn’t been thrilled with his decision to spend the majority of his time rehabbing from shoulder surgery in his native Florida rather than at Valley Ranch. Jenkins could stay with the Cowboys through the season before leaving as a free agent, but the team also could trade him sooner if the right offer comes along.