I don't know what type of leagues you guys play in, but in an NL a guy like Tomko is well worth owning. In fact his 13 wins alone kept him on someones roster last year in my league. I agree in a mixed league he's not worth owning, but he will be on a team in my league.
As far as the Giants rotation, I agree it isn't the type of rotation you'd expect from a teams that's been consistently approaching winning 100 games, but it is far from awful.
Schmidt is one of the best pitchers in the NL, in the game really. Rueter is an awful fantasy pitcher but he does three things well, get himself into trouble on the mound, get himself out of trouble on the mound, and WIN. Williams is a great up and comer with #2, maybe even ace potential. Lastly, Hermanson and Tomko are veterans who are capable of putting up good numbers (look at Hermanson's numbers in his starts with the Giants, very good), if one of the two has a solid season the rotation will be fine. Sorry just got to defend my Giants.