The Transaction Oracle offers its thoughts on the Colby Lewis signing...and while there are several paragraphs, the first sentence is a good summation of TO's take:
Terrific, terrific signing by the Rangers.
ZiPS projects a 4.39 ERA in 176 innings from Lewis as a Ranger, and while, as Szymborski notes, there's more potential variance in it because of the issues regarding Japan to US translations, something close to that would make this signing a steal for Texas.
Evan Grant also offers thoughts on the Lewis signing and what it means, noting that a lot of teams are trying to be sure they can go 7 or 8 pitchers deep with their starters, to provide for quality depth and insurance in case of injuries or struggles. Grant thinks Brandon McCarthy will start the season in AAA, although given his service time, I'm not sure he can be optioned without clearing waivers.
UPDATE -- Just saw in the comments at BTF that CHONE has a projection for Lewis, as well...3.86 ERA in 168 innings. I'd take that.