It's important, every once in awhile, to examine oneself. The unexamined life is not worth living, they say. In this world of relatively inconsequential baseball analysis, it's easy for us to say things and then forget about them two months later. We move on to more, better data. This isn't a moving on post. This is a "I said something earlier, so let's check in to see what's happening" kind of thing.
On April 8th, 2015 I wrote an article for this website stating that Edinson Volquez's sinker needed to be better. WHOA! IMPACTFUL ANALYSIS THERE KEVIN. The basic premise of my article was that Volquez showed very inconsistent command with his sinker. In order to be better this year, he needed to locate his sinker better. Let's look!...at this year's zone locations. Click the article above to see last year's sinker locations.
Against lefties, Volquez is doing a better job of keeping the ball away and "more" down. The biggest change is against righties. He kept the ball somewhat focused low and away against righties last year, but he's done a fantastic job of keeping the sinker down this year.
In addition to location, Volquez has added a little bit more horizontal run; it's getting almost an inch more arm-side run. He's also added half a mile per hour in velocity.
Look. Volquez appears to have better command of his bread-and-butter pitch, he's throwing it harder, and it's getting more movement. The results have followed. His whiff rate on the pitch has rebounded, and hitters are doing much less damage on the pitch: .275/.374 BA/SLG. Hitters clocked his sinker to a .292/.454 BA/SLG last year.
So, I said his sinker needed to improve. It has. Good results have followed. Yay! A side effect of a more effective sinker has been a much more effective changeup. Volquez's whiff rate on his changeup was 14.6 percent last year. It's 22.7 percent this year. Hitters have a .111/.111 BA/SLG against his changeup. That's just hilarious. His changeup is his go-to weapon with two strikes, and it's worked out swimmingly for him. By Fangraphs' pitch f/x linear weights (per 100 pitches), Volquez's changeup has been the 8th best changeup so far, right ahead of Cole Hamels, an "ace" known for his changeup. It helps that Volquez has done a good job of locating the changeup better too. It's more low and away to both lefties and righties.
All this has led to Volquez being worth 1 fWAR already, which was his total for all of last season. His strikeout rate and walk rates are slightly improved, but it's his homer rate and BABIP that are keeping his ERA below his peripherals. If Volquez's sinker is truly better, then it's possible some of his performance is sustainable.
So what's the cause for his sinker being better -- the extra movement, the velocity, the results. Honestly, I'd like to say it's mechanics. It's almost always mechanics right? Maybe different grips. Maybe not. His release points seem relatively unchanged. I tried to go examine Volquez's most recent start and a comparable late May start from last year when he was with the Pirates. It's hard to draw conclusions from looking at just a few pitches, but it looked to me like he has sped up his delivery this year. I didn't actually time the delivery, nor could I achieve the necessary precision and accuracy of timing with my current internet connection and MLB.tv. It just looked faster.
Having said that, there is at least a plausible basis for improved command upon improved momentum. It is possible that the kinetic chain that is Volquez's delivery lines up better with increased momentum. Momentum and torque are the things that help generate velocity, so increased momentum would lead to increased velocity. Volquez looks like he has a little more momentum, so it's possible there is causation. Without a deeper dive, this is really just a hypothesis.
Overall, Volquez is pitching better. It starts with his sinker. The changeup is potentially a ripple effect. Hitters aren't doing much with his curveball either. Maybe Volquez made the changes on his own. Maybe Volquez just has better control over his pitches. Maybe Dave Eiland had a hand in making a slight adjustment in mechanics. Whatever it is, at least the Royals are reaping the benefits for us to examine.