Arroyo put up similar numbers to Pavano in the AL East back when he was with the Red Sox. And his home park over the last 8 years is a bandshell. Arroyo isn't guaranteed to succeed, but more so than Pelfrey, Albers, Diamond, Correia, Hughes, and even Deduno and Gibson.
I would rather the Twins go after Garza, but if not, Arroyo is still worth it in the current pitching market.
You can never have enough pitching. Ideally, by the end of this year, there are pitchers in the minors pushing for spots, leading to a deadline trade or two.
Imagine that Nolasco and Arroyo put up close to sub-4.00 ERAs and 180+ innings. Hughes improves for the most part, while Correia starts off strong again before fadiing. Mays dominates AAA, along with Gibson, forcing the Twins hand to either demote their #5 pitcher or trade one of the other pitchers. Is that really a bad thing? And if they fail, you still have pitchers at AAA.