It would be easier to say "Sometimes, prominent players who are near free agency surface in trade rumors, even if they are superstars", generalizing is never a good idea, since it always fails, Doiji, my friend.
Also, IIRC, Lowell was mentioned in the Helton trade rumors prior to the start of the 2007 season, but that's just for aclaration purposes.
However, never once during his Red Sox tenure did i hear/read the name Curt Schilling mentioned in trade rumors.