I don't have any absolutes, but one thing I definitely think is that pitchers are a combination of all their attributes. Obviously more control and more ground balls are better, but some pitchers can be effective with other factors which compensate for those.
Over time, when I've looked at pitchers who I thought might succeed but didn't, it looks to me like poor pitches can nullify good splits. For that reason I now favor pitchers with good pitch values when I can. I look for not just a good P1 but a good combination of P1-P2, and the more good pitches the better.