Kevin Slowey was second with (.116) narrowly edged by Ervin Santana (.114) and tied with the mighty Greg Maddux; he was ahead of Cliff Lee (.128), Johan Santana (.130), C.C. Sabathia (.135). Scott Baker's numbers were .142 and Nick Blackburn's .146.
Perkins did not make the cut. Given the situational performance of the starters last season, and disregarding stats like W-L record, and ERA, Perkins was clearly the sixth best starter (behind Slowey, Baker, Liriano, Blackburn and Bonser). Perkins is primarily a fastball pitcher who gets in trouble when he cannot locate his fastball or when he throws it down the middle of the plate (and his tendencies are to do exactly the latter when he is pressing...) His off-speed stuff is hittable as much as a Livan Hernandez fastball and his fastball does not fare much better, because of the aforementioned location problems. At least Livan had his curve as an out pitch:
Pitcher Pitch BAA
Perkins Slider .351
Perkins Changeup .300
Perkins Curve .286
Perkins Fastball .299
Livan Fastball .359
Livan Curve .227
Clearly the Twins have 3 starters (Slowey, Baker, Liriano) who can be #2-#3 starters in any team in the league and can develop into aces, as well as a solid bottom of the rotation starter (Blackburn). I think that a 5th starter is necessary for the Twins to take the next step, and this is not Perkins or Bonser. Perkins and Bonser do have trade value and as I proposed earlier, they can bring valuable players for the Twins, if packaged correctly.
also, here is the "luck" metric (Luck, as measured by the number of extra wins, and short losses the pitcher actually got, versus his expected record. LUCK = (W-E(W))+(E(L)-L) ) of the Twins' starters according the Baseball Prospectus:
Next: potential starting pitchers inside and outside the organization