It’s no secret the Cardinals will devote considerable resources this off-season to acquire a new left tackle. To me, it became obvious last Sept. 26, talking to General Manager Steve Keim, as the Cardinals practiced in Sarasota, Fla.

It was spitting rain. Part of the field already was under water from days of storms. But Keim could have stood there for an hour, answering questions about why it was so hard to find a quality left tackle in the NFL.

Three weeks earlier, the Cardinals’ Levi Brown has yielded three sacks and two forced fumbles to end Robert Quinn in a loss to St. Louis. Less than a week later, Keim traded Brown, a first-round pick in 2007, to the Steelers.

The Cardinals needed a left tackle then. They need one now.

And they are not easy to find, Keim said on that September day, because a good one “has to be 6-4 to 6-6. He has to have a certain length of arm. He’s got to have enough range and mobility. Then you also get the guys who are long and athletic, but they are not physically tough, they are more finesse guys ... and then they (defenders) are bulling the crap out of them and knocking them back into the quarterback.”

Keim wasn’t finished.

“And you also have to be smart enough to learn the playbook. You go out there in the country, and there are a lot of big men. There aren’t a lot of big men with great feet, great athleticism, great range and all of the requirements it takes to play that position.”

The Cardinals don’t have one.

Brown was replaced by Bradley Sowell, acquired off waivers from the Colts at the end of training camp. Coach Bruce Arians consistently described Sowell as a “battler.”

What the Cardinals need, and they know it, is someone so good they can take him for granted.

To obtain that player, they are either going to spend more money in free agency than they would like, or take one high in the draft. They can live through the pain of playing a rookie if it can be attributed to growth, not lack of ability.