Anthony Bass and the Change-Up

Drew Hallowell

Little did you know, the theme for Wednesday was the Change-Up and Anthony Bass fit right in.

Yesterday worked out perfectly. Late Tuesday night, I sent the link to this very interesting fanpost from Dr. Rick out to the rest of the TCB staff. What it did was spurn a pretty in-depth discussion among a few of us about Effective Velocity and the value of a change up.

I just think that those stats are not truly definitive on his pitch due to improper usage. Statistics outcomes are only as useful as the quality of the input data. If a pitch is not used properly, the input is flawed which results in a flawed outcome measure.

This is a quote from me in the email in discussion about Bud Norris' change up since it was discussed several time as to whether he should stop using it. All of the outcome measures pointed to it as a poor pitch. However, the change up is more reliant on pitch sequencing and the previous pitch than any other pitch and if used improperly, it's risk of being unsuccessful increases.

Dr. Rick did a good job of explaining Effective Velocity in that fan post, so be sure to read it. But, I'm going to apply it to the change up.

Take a pitcher who throws a 91 MPH fastball. If that pitch is located in the "7" zone (picture a phone key pad), it is perceived as 88 MPH. Now, take a change up that averages 85 MPH and consider where that pitch can be thrown. That's a 6 MPH difference from standard velocity but is only 3 MPH difference from the perceived velocity. That means The pitch can only be located in the 4, 7, and 8 zones in order to not be within the 6 MPH range (3 MPH above and below previous pitch's perceived velocity). That requires a very good feel and command of the change up.

The discussion evolved into Chris pointing out that the after a large enough sample size, all pitch values have to have some predictive weight to an extent. I have to agree to a degree only in part that after awhile, if there's not an improvement in sequencing, the pitcher is unlikely to do so without a change in the organizational philosophy, pitching coach, ect.

So, I asked Chris what made a change up a bad/good pitch.

What could make a changeup bad, in my opinion:
--too small a variation in velocity compared to fastball (mostly would be a problem for guys with low FB velo)
--no break at all (coming in flat)
--unable to locate it for whatever reason (poor command/control)...maybe because the grip is uncomfortable or unpracticed?
My opinion is slightly different. If a change up is commanded, it can be effective when used properly. No matter how small the change in velocity from the fastball, it can be used with Effective Velocity. A fastball alone can have a 6 MPH range within the zone. Even with a 3 MPH difference, you can move the pitch 6 inches and achieve a 6 MPH difference in perceived velocity, making the pitch less susceptible to solid contact.

Break is a factor, but not a huge factor. The movement can assist in increasing the whiff rate and even ground ball rates, but I don't think it's required to be effective. Lack of movement won't make a change up bad.

The other thing to consider is something that Clack pointed out.

The pitch values are based on the linear weights (like wRC+) of the outcomes for the pitch. So it is susceptible to both BABIP-luck issues (depending on sample size), as well as pitch sequencing issues. For example, the change up might be more effective than it’s pitch value because it’s real value for the particular pitcher is to set up the next pitch. So, the unrevealed value of the change up might be reflected in the values of other pitches which are set up by the change up.


To make the theme of yesterday go along with the change up, the Astros traded for Anthony Bass. But, how does that tie into this discussion? I'm so glad you asked!

I'll let ashitaka explain it to you:

Something that jumped out from Sickles' piece on him:

"In the minors he has shown a decent changeup, although he didn't use it much in his first major league outing according to both pitch f/x and people who saw the game."

So I thought I would look that up:

2011
--> Total pitches: 725
--> Change ups: 61 (8.4%)

2012
--> Total pitches: 1509
--> Change ups: 213 (14.1%)

2013
--> Total pitches: 692
--> Change ups: 61 (8.8%)

Though it's a limited sample of just three partial seasons, it's worth noting that in 2012 he posted his best K/9, BB/9, GB% and xFIP when throwing his change up significantly more. Maybe it's not so much the change up, or how good it us, but his talent for sequencing it, like you guys were talking about earlier. No way to know, but I thought it was worth pointing out once I saw it.
We already know that the Astros are very big proponents of their minor league pitchers developing an effective change up. Buying low a pitcher after a down year who used their change up significantly less than a much better performing season would fit the organizational philosophy. So, it's reasonable to gather that the front office feels they can get the better version of Bass by utilizing Effective Velocity and improving the change up usage.

Evan Drellich added another interesting wrinkle to the situation last night with this article,

There’s a baseball facility in Montgomery called Ron Wolforth’s Texas Baseball Ranch, and Bass spent a few days working on his mechanics with the help of video.

"Nothing too drastic," Bass said. "Because he said, ‘You know what Anthony, pitching is unique — you pitch a certain way, you’re not going to pitch the same as someone else.’ Basically, he saw something in my arm. I was kind of letting it drag behind me and it was hard for me to consistently throw strikes down in the zone. I kept leaving things up. He’s like, ‘Well, yeah you’re trying to pitch down and your arm’s lagging behind and it was trying to catch up with your front half."

Bass left with drills to help his arm stay closer to the back of his head through his delivery, and he wants to use his legs more.

You mean Bass received instruction at the facility that Brent Strom just spoke at?

Another interesting tidbit is that his velocity was down and he couldn't keep pitches down, and as we just discussed, the change up has to be used properly. If his velocity was down, it limited when he could use his change up based on when he can throw it to stick with Effective Velocity and it he couldn't locate pitches down in the zone.

Take a look at this plot:
Now this one:
Don't spend too much time looking at the exact values and the consistent up and down of each plot. Notice that in the first image, the plot has a generalized hump throughout the season. The second plot is a bit more consistent.

The first image is Bass' vertical release point in 2013 and the second is the vertical release point in 2012. Bass had a much more difficult time repeating his mechanics in 2013 as opposed to 2012, which resulted in a varying release point and a decline in command.

Essentially, the Astros are looking at Bass and thinking that they can fix the mechanical differences between 2012 and 2013 and he can return to his 2012 success. Which is entirely possible.

The Astros could be getting the pitcher who posted a 4.02 FIP and 4.04 xFIP in 2012.

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