Tempe and the Cardinals negotiated their contract more than a decade ago, when the team first relocated from St. Louis. The city agreed to spend up to $6.5 million to help build the $11.3-million headquarters and practice facility as an incentive to keep the team in Tempe. The Cardinals currently play in Sun Devil Stadium at Tempe's Arizona State University.

As part of the deal, the Cardinals didn't have to pay rent for the first 10 years because of their investment in the facility. But starting this year and for each of the next 15 years the net rent is $74,000, as long as the Cardinals play in Tempe.

However, if one of the other communities vying for the new stadium--Downtown Phoenix, Avondale, and Fort McDowell Indian Community—is selected, the rent will be hiked to $675,000.

That expense could be something that the team could pass on to its new hosts. The clause could give the edge to placing the new stadium in Tempe, at least from the Cardinals' perspective.

Where the new stadium is built will be decided by the Tourism and Sport Authority, which will own and operate the stadium. The TSA has said it will narrow the prospective sites to two by mid-January and will make a final decision by mid-February.

"This gives a leg up to sites in Tempe, but the TSA board ultimately is the one making the decision," says Steve Betts, a Phoenix attorney representing the Cardinals.

The Cardinals will have some say in where the stadium will be built because the team is contributing $85 million to its development.