The beauty of pitching: The changeups of Trevor Rosenthal and Michael Wacha

Over the course of 200 to 300 years, baseball has established itself as a beautiful game. Some people love offense. Some people love pitching. Some people love home runs. Some people love triples. Some people love Aroldis Chapman-like heat. Some people love off-speed pitches. Well, in my 23 years of life, I have yet to find anything more beautiful (in the game of baseball, that is) than a perfectly-thrown changeup. More beautiful than an Adam Wainwright or Clayton Kershaw curveball, you ask? To be honest, there's something about the simplicity of a changeup that is slightly more appealing to me. Luckily, we are blessed, as Cardinals fans, to have two pitchers at the major league level with absolutely incredible changeups—Trevor Rosenthal and Michael Wacha (get well soon!).

As you know, most good changeups start with the pitcher having a good fastball. As we have learned over the last two plus seasons, both Wacha and Rosenthal clearly have good fastballs. In fact, the threat of Rosenthal's 98+ MPH fastball is likely a very significant contributor to the overall effectiveness of his changeup. However, having a good fastball doesn't automatically mean the pitcher will have a good changeup as well. As you will see from the PITCHF/x data that follows, both Rosenthal and Wacha have good changeups, independent from their fastballs.

Rosenthal changeup PITCHF/x data (career):

Other pertinent information about Rosenthal's changeup is that it has a 9.12 GB%, and he has yet to allow a home run on the pitch (362 pitches) in his career. On average, his vertical release point is less than one inch (0.96 inches) lower on his changeup than his fastball—a virtually unnoticeable difference for hitters standing 60 feet, six inches away. The velocity drop-off of 9.84 MPH from his fastball is just about perfect—leading to whiffs on 44.55% of swings.

Wacha changeup PITCHF/x data (career):

Wacha's changeup has a 12.57 GB%, and he has allowed just a single home run (668 pitches). On average, his vertical release point is 1.08 inches lower on his changeup than his fastball—also a virtually unnoticeable difference for hitters. Given the fact that he throws his fastball 4 MPH slower than Rosenthal, Wacha's velocity drop-off of 7.48 MPH isn't as exaggerated as Rosenthal's, but it is still in a range that allows for it to be effective.

So, why do changeups work so well?

There are numerous reasons behind why changeups are successful at the big league level, but for the sake of this post, I am going to focus on three. First, they are thrown from the same (or at least a very similar) arm slot as the fastball, so that the hitter cannot initially distinguish a difference between the two pitches. Second, the natural decrease in velocity (ideally: 7.5 to 10 MPH) leads to hitters being off-balance which subsequently leads to many swings and misses. Third, late tailing movement (mimicking a good two-seam fastball) often leads to weak contact (aka: low LD%'s, low HR%'s, high GB%'s).

And for your viewing pleasure...

Rosenthal changeup in GIF form:

Wacha changeup in GIF form:

Concluding thoughts:

If the second GIF doesn't get you hyped up about Wacha returning to the mound someday, then you should probably check your pulse. The Cardinals are hoping he can begin a throwing program in a week or so, but if this affects his long-term health, I wouldn't be opposed to shutting him down for the season. Rosenthal's long-term success, whether it be as a closer or a starter, will be largely dependent upon the continued effectiveness of his changeup. He is throwing it at a higher rate (16.53% in 2014), and it has been a key put-away pitch for him, especially against left-handed hitters.

Credit to Matthew Streeter for creating the GIFs used in this post. Give him a follow on Twitter: @mstreeter06. Also, credit to BrooksBaseball for providing easy access to both pitchers' PITCHF/x data.