Well, here's a couple looks at what Vanover did to Liriano and the Twins today. Two looks, from the ump's perspective. Basically, he refused to call a low strike. The Yank Me pitchers didn't throw the ball there, and thus weren't hurt. The Twins did a great job of "keeping the ball down" (where have I heard that phrase... hmm... tip of the tongue...) but Vanover evidently felt the Yankees should only have strikes called on indubitably homerable pitches. You can't ask for all those balls to be strikes, but some of them?
In addition, a look at the second picture shows he had a few cracktacularly bad "ball" calls (green triangles/squares pretty much smack in the middle of the zone) against both teams.
The Twins seem to have this problem every year when they play the Yankoffs and Bahston on the road. You can say he should have adjusted, but it remains that Liriano was making great pitches over and over and getting virtually none of them called. There are like 10 low-edge pitches Liriano could easily have had called strikes that weren't, a handful more just a couple inches off the corner, and only one strike call in his favor (belt high just off the plate).
BTW, clicking on these should make 'em bigger. Used non-normalized for the second because the triangles piled up on top of each other too much in the normalized version.