The first three WRs taken in the draft all look pretty damn good so far... London, Wilson and Olave. Jameson Williams will be a stud. The 5th WR taken, Dotson, has also been very good. I'm keeping my eye on Pickens, Pierce and Moore who were all taken shortly after Thornton in the 2nd round. Moore's playing time has been limited so far. Pierce is averaging 20 yards per reception over the last two weeks. Pickens has been productive considering the WR depth in Pittsburgh and the lousy quarterbacking. Shakir is worth keeping an eye on too, I can see his usage going up in that explosive offense.
Obviously it's not a good sign that Thornton, with his skinny frame, got injured with the very first hard tackle he took. He'll be way behind much of the WR rookie class by the time he gets back on the field (with probably a limited role).