It will be true sometimes with certain pitchers that they'll reach their career peaks very early, even before they get to the majors or hit their 20th birthday. This seems like it might be the case with Bumgarner, who no longer is the upper 90's pitcher he was a couple of years ago at Augusta. I certainly hope it's the case, because the pitcher I saw a couple of years ago was considerably worrisome and this one's not. That said, he could still be a dangerous foe tonight or any given night, and in the future and it probably wouldn't be wise to overlook him. Tonight will mark his third career MLB start, his first at Coors Field.
In the PCL, Bumgarner has been surprisingly sheltered, getting most of his starts in friendlier pitching venues such as Fresno (the Giants AAA home), New Orleans and Oklahoma City. He only had four starts in the PCL's most hostile environments for pitchers, two in Las Vegas and one each in Salt Lake and Reno, with no starts in Albuquerque or Colorado Springs. In those four Utah/Nevada starts he gave up 32 hits and 8 walks in 21 IP, that's not good. Only six of those hits were for extra bases, which is better and since two of the starts came at the very beginning of the season, it would be conceivable that he was still stretching out and not quite ready for the year to start at the beginning of April.
His platoon splits are pretty heavy, so it should be no surprise that the Rockies are stacking what right handed hitters they can against him. Bumgarner has been a little lucky this year, but not much. Altogether, he's a decent third starter candidate. The Rockies will have the advantages of their home park and expected rookie inconsistency tonight, however, so this is a game they should win, as long as home Aaron Cook is awake and ready to go and doesn't sub out for the road version.