Unfortunately for the Diamondbacks, the Seattle Mariners are on Upton's no-trade list.

The Diamondbacks have felt they have a good potential trade match with Seattle for Justin Upton. But remember: They're on his no-trade list.

— Buster Olney (@Buster_ESPN) January 7, 2013

For the last few seasons, Upton has been on and off the trade block. Whether or not to keep the 25-year-old outfielder has been the main discussion surrounding the organization.

The addition of outfielder Cody Ross to an already crowded depth chart that includes Jason Kubel, Gerardo Parra and up-and-comer Adam Eaton -- along with Upton -- likely led to an increased probability of the D-backs parting with one of their outfielders.

Kubel was then thrown into the trade rumors along with Upton, catching the eye of the New York Mets and Baltimore Orioles. However, the D-backs know Upton provides the better return value of the two.

The latest Upton rumors point to the two-time All-Star being moved to either the Mariners, San Diego Padres, Atlanta Braves or Texas Rangers, with the Mariners being the latest front-runner.

The Padres trade rumors involved third baseman Chase Headley for Upton, though talks failed to progress.

While the Braves and Rangers have prospects and talent to offer, it's hard to see from Towers perspective of who the Mariners have that will convince the D-backs to part with the former number one overall pick.

But if Towers and the organization are favoring the Mariners like Olney reports, the Diamondbacks would have to seek the approval of Upton himself.