According to Ken Rosenthal of Fox Sports, the two teams had a deal done; however, everything was contingent on Upton's approval.
The Mariners were ready to send the Diamondbacks pitchers Charlie Furbush and Stephen Pryor, infielder Nick Franklin and outfielder Taijuan Walker. All the names mentioned are prospects, and Walker is projected to have the highest ceiling of the group according to baseball experts.
The Mariners have been looking for a bat this offseason and Upton could have made a difference out there with their offense; however, it looks like Seattle along with the Toronto Blue Jays, New York Yankees, Boston Red Sox and the Chicago Cubs are part of his no-trade list according to ESPN.
I could imagine Upton turned down the trade to Seattle because of their relatively large ballpark, which in turn would potentially affect his offensive numbers.
Upton has long been rumored to be a candidate to be traded from Arizona due to his relatively affordable team-friendly contract (under control for another three seasons and will make $9.75 million in '13), the franchise's finances and a perception that he is not happy with the team.
Arizona general manager Kevin Towers has made it known that Upton is available - at a price.