You are being a bit bearish in your approach to the overall assessment.
When your lineup takes a dump, pitches tend to press. When a pitcher presses for perfection, the wheels fall off.
Each pitcher does not respond to the same approach. What worked well with Hammel or Chen, does not mean that it works for Matusz or Arrieta. Conversely, Petersen may not have gotten through to anyone on the starting staff to begin the season. It is why I said it was imperative to add additional roving pitching instructors and double the efforts. It increases the "he gets it" odds.
How can so many other pitchers go from one ear to another and turn lights out. AJ Burnett ring a bell, how about the own group of Hammel.
I feel you are writing off way too prematurely. Some guys may never do well in Baltimore, some are built for other places, but all are quality arms. It depends about the person being able to get through to them and bring out the potential.