Casey Fien has been quite the revelation for the Twins. Over the last two seasons, Fien has struck out 26 percent of the batters he has faced, and walked just 5.8 percent, all while managing a permissible home run rate. His relief success is interesting for two reasons. First, he got a chance in the Majors with the Tigers in 2009 and 2010, both small samples, and struggled. After he pitched for the team in 2009, he was actually claimed off waivers by the Red Sox, and then the Blue Jays, and then released by the Blue Jays. He was signed again by the Tigers and got into two games with the MLB team. He didn’t pitch at all in the Majors in 2011, pitching in the minors for the Astros, who would release him in August. He got a shot with the Twins AAA team in 2012 and really wasn’t spectacular before being called up and appearing to establish himself in the Majors like he has done.
The other thing that makes his success interesting is that his fastball is really mediocre, a couple of MPH slower than league average for a right-handed reliever. Like many pitchers, Fien has a 4-seam fastball and a moving/2-seam fastball. With the Tigers, he got just one swinging strike with the moving fastball, and gave up 9 contact plays. The swinging strike was on an at-bat that he would end with him giving a homer on the pitch. With his 4-seam fastball, he got 10 swinging strikes out of 128 pitches, but still gave up 29 contact plays with the pitch. So far as a Twin, he has a 12.1 whiff percentage with the fastball. His velocity hasn’t gotten better, in fact, it has lost a tick (going from 91.38 MPH to 91.24 MPH). There doesn’t seem to be a significant change in how he is locating the fastball on average either:
Fien has lowered his release point since his days with the Tigers, but there is no significant change in horizontal release point. It is unlikely that this is contributing to his success. However, his moving fastball has gotten better as well (1.6 contact plays per every swinging strike).
One thing that may have contributed to his success is the rise of the changeup. With the Tigers, he threw just one pitch that was classified as a changeup, while with the Twins, he is throwing a changeup nearly 19 percent of the time according to the MLBAM tags. It has been a decent pitch, with a 13.4 % whiff rate, with 2 out of his 7 homers given up as a Twin coming on it. This could, at least theoretically, make his fastball better. It would be difficult to test, because you would have to find pitchers who have increased changeup usage (and only include pitchers who had an effective changeup) and then see if their fastballs improved (without velocity increases, since a velocity increase would make it more effective anyway, and it could just mean that the tags are correctly labelling pitches changeups that were previously labelled as slow fastballs). I took a crack anyway, and looked at the 51 pitchers that throw changeups and have a qualified amount of innings in both 2012 and 2013. It is an arbitrary number, and not as big as Fien’s, but I decided I would look at pitchers that threw changeups 5% more of the time in 2013 than in 2012 according to MLBAM tags. I got 7 pitchers, Jimenez, Leake, Verlander, Saunders, Blanton, Guthrie, and Arroyo.
Verlander (1 MPH), Jimenez (.5 MPH), and Blanton (.9 MPH) are all velocity decliners, so we have to tread carefully, as they may just be having more fastballs classified as changeups. Brooks Baseball’s manual tags have us throwing out Verlander, but keeping Blanton, and just muddies the water with Jimenez with the way they have been classifying the splitters and changeups. Verlander’s increased changeup usage seems to be non-existent and just a product of slower fastballs. We will keep Blanton and Jimenez though.
According to Fangraphs’ wRC +, Arroyo’s fastball has improved this year, Blanton’s has been much worse, as has the fastball of Joe Saunders. Jimenez and Leake have improved, but Guthrie’s fastball has regressed badly. It doesn’t seem that there is much evidence that increased changeup usage helps the fastball, but we have to remember that Fien basically invented the pitch. It wasn’t that he just started throwing it more, he started throwing it a lot, after not throwing it really at all as a Tiger. There is no example of that in the pitchers we look at. Fien invented a new pitch, and it gave him a new and effective tool in the toolbox. Considering that it is difficult to find anything else is doing to make his fastball better (and as the numbers show, it is indisputably better), it seems that the logical conclusion is that it is the heavy usage of the changeup. If the arm speed is there, meaning he doesn’t show that he is throwing the fastball or changeup before the ball is delivered, then it is entirely possible that hitters try to sit on the changeup, only to get burned by the fastball, even though it doesn’t have plus velocity.