I'm not big on fWAR for Dickey, because he's constantly outpitched his FIP/xFIP pretty much every year, some years by half a run or more. I'm guessing this is mainly because of a lot of weak contact / ground balls generated from his knuckler. In his 3 years with the Mets before he came here, his ERA was anywhere from 0.5 to 0.8 runs lower than his FIP, and about 0.5 lower with the Jays. To be able to do this so consistently can't be ignored.
He's known for his slow starts, so I'm not too worried yet. If it's mid-June / early July and he still hasn't picked up then that's a different story.
He's bound to regress eventually due to age, and maybe this is the year, but that's really not because FIP (fWAR) is a better indicator of future performance than bWAR... that's just because he's getting old and eventually every player hits some sort of wall / performance drops off a cliff.