Francisco Liriano burst upon the scene in 2006 with a 2.16 ERA in 121 innings. His career has been up-and-down since then, with little time spent in the middle. He missed all of 2007 with Tommy John surgery, then returned for a shortened but productive 2008. The 2009 season saw him susceptible to homers, walking more hitters than he ever had in the majors, and once again missing time with injury.
The Liriano of old appeared in 2010, striking out over a batter per inning, posting his strongest strikeout-to-walk ratio since his rookie campaign, and coming the closest he ever has to 200 innings with his lone 30-plus start season. Since that season, though, that Liriano has disappeared, replaced with the unproductive, oft-injured version. Thanks to his awful start this season -- 9.45 ERA, 1.1 K/BB -- Liriano now finds himself in the Twins' bullpen.
In order to see what's wrong with Liriano, other than an intractable case of the terribles, we need to know what made him so effective in the past. PITCHf/x data wasn't available back in 2006, when Liriano was a 22-year-old, up-and-coming stud, so that leaves us with essentially the 2010 campaign. Enter Brooks Baseball:
The numbers you see above are z-scores. They allow us to see not only whether a pitch is above- or below-average in a particular area, but also whether or not by a significant amount. Hitters didn't foul off many of Liriano's offerings in 2010, instead swinging straight through his slider -- the pitch he used the most -- or getting on top of his four-seamer and change-up, hitting a grounder. His sinker wasn't especially effective for grounder purposes, but with his other pitches inducing groundballs, it wasn't an issue.
His change-up worked well for him, with 61 percent of them going for strikes, and when they were put into play, it was generally on the ground. It was the pitch he used least, but it was his second-most productive pitch after his slider, according to the pitch values at Fangraphs. The four-seamer and sinker, on the other hand, both trended negatively.
Fast-forward to 2011, and things start to change in terms of results. In essence, his slider became less effective, and in turn, he couldn't get away with his less-useful offerings as well as he had in 2010:
None of his pitches brought about grounders as they had in the past, but his change-up at least started to see swings-and-misses to make up for it. Part of the reason his pitch values dropped in 2011 was due to throwing nearly 60 fewer frames, but it was also thanks to less-effective looks overall. Liriano was something of a four-pitch pitcher with two pitches of merit, one of which wasn't even doing what it had before.
The velocity on his four-seamer fell from 94 to 92 miles per hour, and his other pitches -- excepting the slider -- saw a similar dip. He dealt with left shoulder inflammation during spring training, and again in late May, with the second time around leading to the disabled list. This might have been the key to his velocity problems, but to this point in 2012, there's been no word about his shoulder. Yet, his velocity never recovered.
The change-up doesn't seem to be fooling anyone anymore, with the pitch being launched as a fly ball far more often than a change-up should. It's also not inducing swings-and-misses, another sign that maybe the opposition has him beat on the pitch. His slider isn't getting misses now that it's seen some velocity loss, instead picking up fouls on swings. It also hasn't recovered the ability to force grounders, like it had in 2010.
Liriano has a .369 batting average on balls in play, and that's helping to fuel his horrific ERA. The problem is, he's also gone from multiple useful pitches to one, and now seemingly zero over the last three seasons. The Twins aren't helping, but they aren't hurting, as their 70-percent Defensive Efficiency overall is just a little worse than average.
A return to the bullpen might help Liriano rediscover some of the velocity he has been lacking the last two years, and will also allow him to discard some of his less useful pitches, or at least be forced to show them less often. At this point, with his velocity and movement diminishing, the Twins had to try something. This iteration of Liriano looks like a lost cause, so there's little to lose from moving him out of the rotation.