1. Maddog — Feb 27, 2008 @ 11:04 PM
This actually helps quite a bit. I’m going to place a link on the sidebar to this under ACB Links for future reference. Thanks, Harry.
PITCHf/x - definitions
Posted by on 02/27/08 at 09:25 PM • 27 Comments
Lingo. Jargon. Let me do what I should’ve done before - define a few things in one place.
This is not meant to be exhaustive, but defines the things I commonly refer to in my PITCHf/x posts.
Speed - this is almost always “start speed” in MPH. end speed is also measured. This is the calculated speed at release
y0 - this is a key number - y is the distance from home plate (which I think is actually at 1.4 ft., not 0). y0 is the release point. Actually, it is where the system picks up the ball and starts tracking it. y0 seems to have settled on 50, but has varied from 40 to 55.
x0 and z0 - what we typically refer to as a release point. It is where the ball is at y0 (0 is time in seconds, btw). x is lateral and z is vertical. 0 is the ground for z. 0 is the middle of the plate/rubber for x. A negative x value is to the catcher’s left, or inside on a right-handed batter. Most, if not all, of the graphs I use are from the catcher’s perspective.
pz and px - where the ball crosses the plate. I think Alan Nathan has noted that py is 1.4, as noted above.
OK, now on the the good stuff. The key thing is how we view the movement of the pitch relative to what a straight/not spinning pitch would do if only gravity was acting on it. In other words, when we look at vertical movement - expressed as pfx_z - it is inches up or down from what would’ve happened with gravity alone. I’m not 100% 0 is really 0 here, I need to find that article again ...... pfx_x is horizontal movement, relative to a straight path between x0,z0 and px,pz, that is caused by spin.
The typical chart is the PFX stuff, which is usually the most telling and tries to capture movement. It’s sister chart is also derived spin info and includes RPM and Degrees. That is often helpful is splitting two-seamers and four-seamers, which can look very much alike in a PFX chart.
To identify pitches, I use eyeballs or k-mean clusters. Google k-mean clusters if you want to know more, but it is a decent way of dealing with this mathematical problem, without being baseball specific (beyond the inputs, which I usually set as speed, pfx_x, pfx_z, rpm, deg).
Hope that helps deciphering my stuff.
Comments
2. theantigoat — Feb 28, 2008 @ 12:30 AM
Uhhhh, huh???
You guys joke about being dumb hicks, well I truly am a dumb hick. Actually redneck better suits me. I own a big diesel truck, I live in Texas, when I say flower it sounds like flyer, when I say wrestle, it sounds like wrastle, + I did’nt graduate HS. Interpretation, this post is WAY over my head. I do, however, like baseball.
3. Jame Gumb — Feb 28, 2008 @ 07:07 AM
The Vegas line has nothing to do with being right, and everything to do with getting a sufficient amount of action from all sides. They make their money off of the vigorish, not by betting against you.
While this is true, CW, Vegas is very good at setting spreads, lines and over/unders. If they set the o/u for wins at 92, there’s a very good chance the team wins 89-95...though I don’t think CHC has a chance in hell to win 95 games.
4. Jame Gumb — Feb 28, 2008 @ 07:19 AM
I better not be seeing Koyie Hill on this roster at any point in 2008.
Because you don’t want the team to win in 2008?
5. Jame Gumb — Feb 28, 2008 @ 08:57 AM
Murton has been–hands-down–absolutely THE best hitter with the most power (both in “traditional†BP and “live†BP sessions) at Cubs ST so far.
-- AZ Phil
6. — Feb 28, 2008 @ 09:03 AM
Lol, it’ll be funny if Murton turns into a legitimate starter, now that he’s finally blocked long-term. The only way he could find a starting job on this team is if Pie struggles, and K-Fuck moves to center.
7. Jame Gumb — Feb 28, 2008 @ 09:29 AM
The only way he could find a starting job on this team is if Pie struggles, and K-Fuck moves to center.
Would he really be worse at SS than Theriot? OH NO HE DI’N’T!!
8. Maddog — Feb 28, 2008 @ 09:47 AM
Ryno, where are those links to the Cubs on WGN that you’ve posted before? I’d like to listen to some of the game today at least since it’s finally baseball season...almost.
9. Maddog — Feb 28, 2008 @ 09:49 AM
I’ll buy that Murton actually has decent power when I see it in real games. I’m just going to be glad when he’s gone from this team. Some other fans can complain he’s not getting enough playing time.
10. Maddog — Feb 28, 2008 @ 09:50 AM
Would he really be worse at SS than Theriot?
Probably not. The sad thing is I’d actually put Murton at SS before I’d start the season with Theriot at SS. I’d give the job to Carlos Zambrano over Theriot if it were my decisions.
11. — Feb 28, 2008 @ 10:32 AM
u have a link for that Arizona Phil thing Ryno? I might want to read the whole thing,
12. Jame Gumb — Feb 28, 2008 @ 10:33 AM
I might want to read the whole thing,
Let me know if/when you really do and I’ll post it.
13. — Feb 28, 2008 @ 10:34 AM
I did have a link posted for dylanj in this post, but ryno correctly noted that he wasn’t positive that he wanted to read it, yet, so I’m removing the link.
14. — Feb 28, 2008 @ 10:35 AM
Let me know if/when you really do and I’ll post it.
Oh, Fuck! I forgot to make sure that he was sure he wanted to read the whole thing.
15. Jame Gumb — Feb 28, 2008 @ 10:47 AM
Ryno, where are those links to the Cubs on WGN that you’ve posted before?
Did you even look?
19. Jame Gumb — Feb 28, 2008 @ 10:59 AM
No. That’s why I asked you.
OK. I actually did a quick search and can’t find it either. I’ll see what I can do…
20. Maddog — Feb 28, 2008 @ 11:01 AM
The search function for this site is much better than the old one, but “better” almost always means more complicated and I haven’t taken the time to figure that shit out yet. In the admin panel you can search only comments if that helps you.
21. Maddog — Feb 28, 2008 @ 11:01 AM
i actually do want to read it
Ryno, TD and myself have decided that you can’t handle it. You’ll thank us later.
23. Maddog — Feb 28, 2008 @ 11:03 AM
I don’t believe you.
I don’t believe him either, but maybe we should allow him to read and force him to write us something like a book report to make sure he really did read it?
24. Jame Gumb — Feb 28, 2008 @ 11:05 AM
maybe we should allow him to read and force him to write us something like a book report to make sure he really did read it?
I don’t want to be responsible for the images that will haunt dj if he reads that. It’s not for the faint of heart.
25. Maddog — Feb 28, 2008 @ 11:10 AM
I don’t want to be responsible for the images that will haunt dj if he reads that. It’s not for the faint of heart.
That’s a good point. We’re a lot stronger than he is and I’ll admit that it’s caused a few nightmares last night.
26. — Feb 28, 2008 @ 11:28 AM
by all accounts, dylan can’t handle AZ Phil within 48 hours of bedtime.
27. — Feb 28, 2008 @ 11:45 AM
here, see if you can handle some of this lower intensity Rob G. first, and maybe we’ll get you some AZ Phil later.
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