The first thing to remember about WAR is that it does not do as good a job as a predictive stat. The next thing to keep in mind is that the rotation was not expected to be our strength, so the low WAR total should not be that alarming.
That said, much of the low WAR total from 2014 is a result of injury and/or lack of innings pitched, particularly in Masterson's case. Once again, I'll point out the in 2013 Masterson was a very good pitcher, so I don't think his 2014 WAR was a good indicator of what we should expect this season, due to him being injured. Yes, he was a risk, but it wasn't an insane risk.
There was really no reason to expect Porcello, Miley, or Kelly to be big risks. Miley has more or less given us what we expected. Kelly has pitched about to career norms, ERA aside. He is not one who has ever pitched close to 200 innings, hence part of the reason for the low WAR, but he should have been serviceable for at least the first half. Neither one of them were expected to be front line starters.
Porcello has fallen way short, but there was no reason to expect that.