Interested teams are starting to wonder how just serious the Rays really are about trading James Shields.

The Rays are said to be seeking "north of Greinke," referring to the three-prospect package the Brewers got for star pitcher Zack Greinke, who is a free agent after the season. So if they do trade him, it will obviously be expensive in terms of the prospect return.

Shields has drawn interest from the Rangers, Dodgers, Braves, Indians and Cardinals, among others.