Javy is among a group of sabermetric-freak pitchers who have inexplicably bad results in ERA to go along with generally solid WHIP, good walk rates, and high strikeout rates. One common denominator among these sorts of pitchers is that their strike-throwing tendencies are almost too consistent--they don't walk people, but that's b/c they leave a lot of hittable pitches (especially fastballs) around the plate. Vazquez unsurprisingly has a pretty high career LD rate, and check out his year-to-year numbers:
04 - 19.1%
05 - 22.9%
06 - 19.5%
07 - 16.8%
08 - 22.5%
Which one looks like the outlier here? Unsurprisingly, 07 was the only year he went under 4.00 in ERA.
The other common denominator is high FB/GB ratio. Vazquez gives up a ton of homers, more than 1 every nine innings, or essentially almost 1 per start. Homer-happy pitchers tend to be harder to stomach in fantasy b/c they might throw 6 good innings and then give up 2 homers and end up with 4-5 ER on a night where they pitched well except for a few mistakes...whereas a guy like Brandon Webb can make 20 mistake pitches in a given night but most of the time batters still can only get line drive doubles off his heavy sinker.