Liriano has a delivery in which he really throws across his body, putting a lot of stress on his shoulder. Sure it makes his pitches tougher to pick up, but the downside is being felt right now. He also throws an extremely high percentage of sliders, putting additional stress on his elbow.
Unless Liriano alters his mechanics and starts throwing more fastballs and changeups, I foresee injury issues in his future.
It's usually the sinker/slider guys that run into injury issues. Jake Peavy throws a lot fo sliders and Brandon Webb throws a lot of sinkers. It is no coincidence they are ailing. Watch out for King Felix in that regard. Verlander, Cain throw a lot of 4 seam fastballs, which are stress free. As is the changeup. They should be okay.
Contrary to popular belief, when it comes to pitchers, injuries are predictable.