Jeff Weaver and Derek Lowe are the only two ERA title qualifiers that have not given up a HR. Weaver is pitching against the Indians tonight. This is a real improvement for him. He usually gives up about 1 HR per 9 IP. You can see it in his ERA this year, 2.92 coming into the game. Interestingly, he seems to be a first half pitcher, so this could just be another good start. Maybe with his thin frame, he tires late in the year. Look especially at his IP and HR allowed:

ERA   W   L  Sv SvOp  G  GS     IP    H    R   ER  HR  TBB   SO
Pre-All Star   3.94  22  25   0   0  61  60  400.0  393  194  175  35  119  264
Post-All Star  5.08  15  23   0   0  43  42  264.0  291  157  149  37   75  177