That's sort of the thing about relying solely on formulas. I'd rule out Callebero and not even consider him using the "eye test". That said, while neither should be BL pitchers, they're pretty much the same guy(slight edge to Guerra) . I use a 5% +/- to "group" players. They fall in the same group. And that group is "career minor leaguer". FWIW, I have different formulas for different parks. I don't have one for SD so I plugged it into my NY formula. That said, I imagine both could be slightly below BL-average in SD. Good control, good pitches, park effects = B/A pitcher.