Again a lot of it does depend on your bench depth for you league and league setup. In HTH with shallow benches I don't think it's that good of an idea because you can run up with a team stacked with SPs and just out-pitch you. In most roto I think it can be great (because you get some good K, ERA, WHIP and even some Ws and Svs per IP that basically stack up with the top aces) and in HTH with deep benches it can be good. Usually the #7 or so SPs aren't giving you the stats you want, so taking up 3 rosters spots there is worth it.
My favorites this year:
Broxton - solid, tons of Ks and each year I think the risks of Saito going down mount. Not saying there's going to be a change, but there's value in the risk of that happening.
Betancourt - solid and Borowski sucks. Yes, yes he does.
Neshek - Not a lot of people are talking about him but besides him being a little overworked at the end of last year, he puts of great numbers, tons of K's and I think Nathan will be traded to a contender.
Jon Rauch - Numbers plus I think Cordero gets traded to a contender.
Hideki Okajima - Solid and likely the backup to Pappelbon should injury strike.
Jeremy Accardo - He gets more into the possible closer talk, but I think he gets enough saves because the Jays will take it easy on Ryan this year (not pitching him in back to back days, etc) and that's if Ryan makes it the full year.
Carlos Marmol - If he doesn't get closer role, he finds himself in this list. Solid numbers and a few Ws and Svs.
Heath Bell - Once again, good numbers. Also Hoffman's like 62 years old I think.
There are a few others - Henry Owens, Duschschschschsererer, etc who may be on this list eventually but come with a little more risk as far as ratios go.
So... there's enough of these guys that you shouldn't be spending even mid-round picks on them. You can forgo that bench fodder hitter or #7 SP in the late rounds and pick up a guy who at the worst will help your ratios and give you enough Ks, sprinkling in a few Ws and SVs to make it worth it. And with many of these guys they have the potential for immediate 10th-12th round value if they become the closer of their teams. How many late round prospects have that kind of potential, complete with helpful stats even if they don't "hit"?