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  1. #31
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    We don't really have a widely available coherent metric for pitchers which tells us how good a pitcher is, independent of his home park and the defence behind (and if anyone feels tempted to say 'ERA' here, read Dave Cameron's article on pitcher evaluation first). FIP and xFIP are the most commonly used general pitching stats we have, but they suffer from the limitation of only considering strikeouts, walks, hit batsmen and home runs. We know there are other things that are mostly under a pitcher's control, and we also know roughly how much control a pitcher asserts over said events. The hope for tRA then was to construct a metric which takes into account every action a pitcher is responsible for and turns those numbers into runs and outs based around a highly logical and transparent mathematical framework.
    That's the introduction from StatCorner.

    The idea is that it measures all events in which the only thing going into the calculation happen from when the pitcher throws the ball, to which the batter either swings or doesn't swing.

    Everything that happens from then on is completely out of the pitcher's control (excluding his defense).

  2. #32
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    How was the relative amount of control a pitcher has over an event determined?

    Since I keep asking questions about pitching stats, are there any web pages I should look at for information?

  3. #33
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    Sure. Read this: http://statcorner.com/tRAabout.html

    As for your question about amount of control, what do you mean?

    A pitcher can control the pitch he throws, and he has influence on whether it's a strike, ball, groundball, line drive, flyball, etc. After that, who knows what happens. Pop ups fall, line drives get caught, flyballs go out in certain ballparks. Over time, all these events have a certain run value.

  4. #34
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    Also, I think we might be leaving simple questions behind

  5. #35
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    Quote Originally Posted by Gigantes4Life View Post
    Sure. Read this: http://statcorner.com/tRAabout.html

    As for your question about amount of control, what do you mean?

    A pitcher can control the pitch he throws, and he has influence on whether it's a strike, ball, groundball, line drive, flyball, etc. After that, who knows what happens. Pop ups fall, line drives get caught, flyballs go out in certain ballparks. Over time, all these events have a certain run value.
    Thanks for the link. I was referring to this line in the explanation:

    We know there are other things that are mostly under a pitcher's control, and we also know roughly how much control a pitcher asserts over said events.
    How do we know how much control a pitcher has over certain events. I gather from the explanation, that these other factors are essentially things that the pitcher does, without the influence of the defense aside from the following: strikeouts, walks, hit batsmen and home runs.

    edit: Yea, sorry. I'm getting a little off track of the topic here. Maybe a mod should snip these posts that veered off of simple questions into another thread.

  6. #36
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    Quote Originally Posted by k_rock923 View Post
    Thanks for the link. I was referring to this line in the explanation:



    How do we know how much control a pitcher has over certain events. I gather from the explanation, that these other factors are essentially things that the pitcher does, without the influence of the defense aside from the following: strikeouts, walks, hit batsmen and home runs.

    edit: Yea, sorry. I'm getting a little off track of the topic here. Maybe a mod should snip these posts that veered off of simple questions into another thread.
    I'm not entirely sure I get what you're asking, but this is what it sounds like. You want to know how much control a pitcher has on those events, like groundball, flyball, etc.? Like an actual value or what?

  7. #37
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    Quote Originally Posted by Gigantes4Life View Post
    I'm not entirely sure I get what you're asking, but this is what it sounds like. You want to know how much control a pitcher has on those events, like groundball, flyball, etc.? Like an actual value or what?
    Yea, that's about it. It sounds as if they're assigning some type of quantifiable value as to 'how much' control a pitcher has over an outcome. So, 'a pitcher controls n percent of all of the variables that determine whether a given pitch is a ground ball or fly ball etc.'

    Now, it's entirely possible that I'm reading into it too much and I'm hung up on the wording of that introduction. If so, what is that line actually saying? Thanks.

  8. #38
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    I can't say for sure, but based on the next paragraph I believe that when they say mostly, that it depends on the type of batter the pitcher is facing. So over time, we can assume that the events are predominantly in the pitcher's control, and there's no reason to read that much farther into it.

    The other thing that they may be considering is if the ballpark affects how the pitcher throws, but for the sake of simplicity they simply let it go.

  9. #39
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    Okay, thanks. I think that I'm misinterpreting what the text is trying to say. I'll stop hijacking the 'simple questions' thread with small details now

  10. #40
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    Quote Originally Posted by Rylinkus View Post
    Actually, I'll expand. Fangraphs uses a different wOBA formula than Statcorner. Which one is the better one in people's opinions? And why? Perhaps this isn't a simple question and warrants it's own thread.
    Fangraphs' is better, IMO. Statcorner doesn't include SB and CS, but incorporates ROE. And I honestly don't know if they use the correct RV scale, because it changes from year to year. I know Fangraphs does.
    My blog- analysis of the San Francisco Giants, Baseball, and Sabermetrics.

  11. #41
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    Alright I have multiple questions, of course one relating too tRA which was asked before but not really answered because the thread died.

    Alright so you now how it shows a pitcher's "true talent level". Well my questions are why does that true talent level change every year, or if in fact it takes a career to figure out the pitchers "true talent level" then would the stat not be as useful if it is after the fact? Again i just have a problem with the phrase true talent level. I think it should be like tru production level for a season.

    And another is why does it seem like VORP is used so rarely? I really like the stat but it seems like its just never used.
    Jackie Bradley Junior.... that is all

  12. #42
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    and this is just something i kind of came up with and it may sound stupid.

    But is there anyway to figure out how man runs a pitcher is expected to give up with specific defenses? like to actual team defenses?

    Like this pitcher should give up this many runs with the Red Sox defense, and this is what he would give up with the yankees defense? So you could figure out if a pitcher would be more valuable to one team as opposed to another?

    And dont worry about saying its a stupid question because i feel there is a good chance it is.
    Jackie Bradley Junior.... that is all

  13. #43
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    when did this become a forum? i am very excited to see this.

    I have recently been getting into sabermetrics pretty hard. I now am a member on Fangraphs, I love their articles and analysis.

    It is nice to get away from the mundane realm of the general MLB forum.

  14. #44
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    Quote Originally Posted by papipapsmanny View Post
    And another is why does it seem like VORP is used so rarely? I really like the stat but it seems like its just never used.
    I'm uncertain as to what the precise formula is for pitchers, but the formula for position players is downright terrible. VORP uses the most basic form of Bill James' Runs Created formula- which is nothing more than AB*OBP*SLG. That's all. Then it uses a replacement level of ~80%, when it should be more around 73-78%.

    As for positional adjustments, VORP has a bad habit of overvaluing first basemen and undervaluing catchers, among other things. Just stay away from it. It'll undervalue the value of a walk just as much as OPS does.

    Baseball Prospectus also has RARP, which is essentially the same thing, but they use a different run estimator- EqR. While it's a step up from basic RC, it still undervalues walks.

    Quote Originally Posted by papipapsmanny View Post
    and this is just something i kind of came up with and it may sound stupid.

    But is there anyway to figure out how man runs a pitcher is expected to give up with specific defenses? like to actual team defenses?

    Like this pitcher should give up this many runs with the Red Sox defense, and this is what he would give up with the yankees defense? So you could figure out if a pitcher would be more valuable to one team as opposed to another?

    And dont worry about saying its a stupid question because i feel there is a good chance it is.
    It's not a stupid question. You'd need specific batted ball data, along with player data for each specific vector under their control. Then you use the player's probability of making the play and adjust accordingly, after putting in park effects.

    What makes it even more complex is that you'd have to simulate the pitcher against the other team- since you're placing the pitcher on another team, that means he'll be facing different hitters at different points in the season. Also, since we're changing the lineup the pitcher is facing AND the defense, that means a simple single allowed changes the entire course of the game.

    You'd essentially have to simulate the whole thing (a la Baseball Mogul), or use an odds ratio (like log5) exhaustively.

    It's best to just place the pitcher in front of an "average" defense based on the run values and out frequencies of each event the pitcher surrenders. And that's what tRA does. But it's still an imperfect model.
    My blog- analysis of the San Francisco Giants, Baseball, and Sabermetrics.

  15. #45
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    i haven't looked through this thread to see if this has been asked/answered...

    i am wondering how a ball is deemed to be a line drive?

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