The four I like to look at (in order that I like to look at them) that I use to make such a judgment of a pitcher:
WHIP - something right at 1 or better
SO's per inning - 1 per inning or more
BB's per inning - a small number like 1 in 4 or better
Batting Average (opponents) - Low average of course and like seeing .225 or less.