I haven't even watched today's game, yet. I have mlb.tv and no cable, so I have to wait about two hours for the replay to be available on demand. But I saw the results. Liriano actually appears to have pitched well.
An oxymoronic "superfically deep" analysis suggests his performance was "really" better: 9 of 22 batters faced struck out, 7 swinging, only 2 walks. Sure, he wasn't inducing groundballs like vintage Liriano, but beggars and choosers and all that.
So I took a look at the pitch f/x data on brooks baseball to see what, if anything, he did differently.
Looking at the year to date (courtesy of his yet-to-be-updated for today's start fangraphs page), I saw that his (overwhelmingly) primary fastball this year has been, as it was in 2010, classified as a 2-seamer. Its velocity has averaged 92.3 MPH, slightly more than 1 MPH less than his 93.5 MPH 2010 fastball. Which is, obviously, not a change for the better.
The larger difference, though, is that where in 2010 Liriano's 2-seamer was an effective "sinking" (i.e. when coupled gravity and as it appeared from a hitter's perspective) fastball, with only 5.4 inches of true backspin-induced rise, this year it's been horribly flat. A fastball with 7.6 inches of true rise is basically a meatball. True, its armside run has been better than ever, but you don't miss bats with horizontal movement, you just create foul balls.
His change-up has been a similarly slower offering, so in terms of separation and, theoretically, that separation's consequent effectiveness, that really wasn't the problem this year. The problem with his change, as others have noted, looks to me to be its lack of downward bite, losing a full 2 1/2 inches of downward movement since 2010. (Like his fastball, it actually had better armside run than it has historically, but all the "apparent" movement is in one, non-bat-missing plane.)
Liriano's trademark slider's velocity has been relatively more diminished, averaging only 84.1 MPH vs. 85.7 MPH in 2010. It has also had an average of 1 inch less horizontal break and almost 2 inches less vertical (effective) sink than it did in 2010. Last year the slider moved similarly, but its velocity was pretty much what it was in 2010, meaning it was still a pretty good pitch. This year, like his other two primary offerings and his 4-seam fastball, it's had negative value. Again, the loss of vertical movement has hurt him.
So what about today? Did he throw with different, better stuff or just control mediocre stuff better and/or listen to Bert's one-size-fits-all coaching?
Well, the news is mixed. His fastball velocity was exactly what it's been all year. His change-up velo, however, was a down 1/2 MPH, creating better separation. Still, that's only a slight improvement. The slider was a shade quicker (.3 MPH), but not enough to account for the drastically better results. At least the velocity changes are in the right direction.
His slider actually had just a little less left to right break (technically, more right to left armside run, but in practical terms and in terms of perception it makes more sense to talk about a "breaking" ball "breaking" in the direction we think of than to tout it for coming closer to being truly straight) than it's had this season. He offset that by slightly improving its downward bite (1.56 inches of rise vs. 1.9 inches in his previous 2012 work).
In general, downward movement seems to be the best kind to have, so that's a trade you wanna make. That said, today's slider still moved a lot more like his other 2012 sliders than it did like his 2010 sliders.
His fastball, on the other hand, had almost as much armside run as it's had this season to date (which, remember, is the one pitch f/x component that's actually improved vs. 2010, so this is good!), while effectively diving down, on average, an additional 1 1/2 inches. Because his fastball was so atrociously flat this season, even that much extra "sink" (technically, non-rise) doesn't make it quite the true sinker weapon it was in 2010, but it does mean it looked more like 2010's sexy version than it did like this season's stinker.
Likewise, while it wasn't "all the way back", his changeup today had effective sink that was closer to his effective 2010 offering (and its 3.4 inches of actual rise) than his 2012 clunker (5.9 inches), with an average horizontal rise of 4.6 inches.
While it may not be easy to imagine Liriano dominating without regaining his velocity, if he can figure out what he was doing differently mechanically (or mentally, if it's indeed an issue with mindset "allowing" his body to effect the effective (ha!) mechanics of which it's capable) and continue to work in that direction there's no reason he has to continue to be the turkey he's been for the first two months of the season. Plenty of pitchers have great success in years following their peak velo numbers.