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Thread: Trying to Understand Every Move They Make: EPVA Stat

  1. #21
    Raptors Republic All-Star ezz_bee's Avatar
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    There is always going to be certain things that aren't measurable. Just as a unified theory of the universe continues to elude humankinds greatest minds, a unified theory of basketball is likely to elude the greatest basketball minds. There will always be room for "the eye test", but we have to keep in mind that it is fallible. Sometimes the gut is wrong, and needs hard statistical proof to get the gut to change it's mind.

    The crazy part is that EPV is just cracking the surface of the potential of what can be done with these data sets. Over time we'll be able to have a better understanding of the impact of the little things.

    The eye test can tell us that Tim Duncan adds a lot of value because he does the little things, but with a data set this huge, it will be possible to assign a value that can give us a comparison to other players in the league. Is Tim Duncan better at setting screens than Tyson Chandler or DMC? How much better?

    You can answer the first question with the eye test, but since it's subjective anyone else can disagree with your perspective and both are equally valid. However, if a large part of the population feels that one player in particular is better at setting screens than another a consensus begins to form, and it's mostly acceptable to play the majority rules card. (After all, reality is pretty much just the consensus of people's perspectives). The second question cannot be answered without a data set like the one synergy sports is compiling. It will be able to tell us (and I'm making this up) that all things being equal, a play where Duncan sets a screen has historically average 1.09ppp, Chandler 1.02ppp, and DMC 1.11ppp.

    Right now this very micro analysis is limited by resources (essentially time, programming abilty, and computer processing power), but those limits will diminish over time. Eventually, we will have comparable data on things like screens, but also we'll be able to find things like, is Amir Johnson a better screener when he sets a screen for the player to go left, or if he sets a screen for players to go right? Maybe we'll find things out that we have never thought of before. Maybe what your center does with his hands in the paint has an effect on chances that an opposing player will hit a corner three. Maybe we'll find that it is statistically better NOT to leave your feet when the opposing player shoots... ever. Or maybe it's good to jump at the rim, but NOT good to jump outside the paint (or six feet or whatever).

    The limit of the eye test is mostly time. It's virtually impossible to watch every minute of every basket-ball game. It's also virtually impossible to process the actions of ten individuals simultaneously. In order for any one person to achieve the same knowledge as synergy's database they'd have to watch every game, multiple times... AND have perfect memory in order to compare game over game. There's still a benefit to watching game tape (and there ALWAYS will be), but Synergy allows for types of analysis that just aren't possible to be done by a single human brain in any reliable way. Also, the eye test always works better for outsiders. It easy for us to see that Rudy Gay shouldn't have been taking contested jumpers or hold the ball for so long, but a tool that helps quantify the opportunity cost of those actions could be the difference between a player understanding and changing his habits (or if he doesn't/won't then to recognize it early and ship him out).

    It's still takes the human brain to work out WHAT to analyze. I'm curious as to what affect covering floor space has on the game. I'm curious about a lot of defensive positioning and defensive choices. Last year the Sloan Sports conference put out a stat about how big men affect shooters when they are within 5 feet. It wasn't a perfect stat, but it did help quantify the proficiency of post defenders in a way that impossible before except in a mostly subjective way. As the tools to analyze the data are more refined the analysis (or stats) that comes out will be MORE reflective of what's is actually taking place on the court (aka accurate!).

    I for one am super pumped about this, and hope that the NBA continues to foster this type of analysis. In time even regular Joes (or Jill's) will be able to afford a subscription to the data (I think RR already has one), AND afford the type of computers it takes to crunch the numbers (probably about ten years until the kind of computer Harvard is using is available in a laptop... just guessing). Once that happens you will have a considerable amount of people with the energy and ability to do fun things with the data that more will come out of it. Right now technological constraints limit the analysis to academics and NBA in-house guys.
    "We only have one rule on this team. What is that rule? E.L.E. That's right's, E.L.E, and what does E.L.E. stand for? EVERYBODY LOVE EVERYBODY. Right there up on the wall, because this isn't just a basketball team, this is a lifestyle. ~ Jackie Moon

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  3. #22
    Raptors Republic Superstar Superjudge's Avatar
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    I have absolutely no interest in any of it

  4. #23
    Raptors Republic All-Star ezz_bee's Avatar
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    Quote Craig wrote: View Post
    I have absolutely no interest in any of it
    haha, and that's totally fair but aren't you interested in how many kilometers Westbrooke runs in a single game versus someone like Eddy Curry? Or how many revolutions a Ray Allen 3 pointer takes on average before it goes in versus the number of rotations on a Shawn Marion 3? Despite all the actual and useful things that can be gleaned from the data, there's also just a ton of cool but mostly useless stuff it can tell us.

    You may have zero interest now, and never have more than 3 out of 100 interest, but if there isn't at least 1 piece of information (or stat) taken from the sportvu tracking system that you find interesting or cool in the next five years, then I will buy you a beer. (Or if not able to physically meet you in the real world, send you the monetary equivalent of a beer purchased from a local establishment).


    EDIT: More cool things it can tell us, who is the fastest player in the NBA? Who is the fastest player while dribbling? Who expends the most energy celebrating after a made basket. Who spends the most time arguing with a referee instead of getting back on defense? What is 1 second of arguing with a referee likely going to cost you in terms of points on the other end?
    Last edited by ezz_bee; Sun Feb 9th, 2014 at 03:38 PM.
    "We only have one rule on this team. What is that rule? E.L.E. That's right's, E.L.E, and what does E.L.E. stand for? EVERYBODY LOVE EVERYBODY. Right there up on the wall, because this isn't just a basketball team, this is a lifestyle. ~ Jackie Moon

  5. #24
    Raptors Republic Superstar Puffer's Avatar
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    Quote ezz_bee wrote: View Post
    ...What is 1 second of arguing with a referee likely going to cost you in terms of points on the other end?
    This is the kind of info that a team can take and turn into "team policies" that have an impact. I think you are right that this info is like a mining claim and there are huge nuggets of value here to be dug up.

  6. #25
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    @ ezz_bee You clearly have an excellent grasp on the sport of basketball and how SportVU + Big Data Analytics is about to change everything. As far as your point about assigning values to setting screens and other things of this nature...that is a flaw that the XY Hoops Group recognizes. They have to make a few incorrect assumptions in order to simplify their programs and algorithms enough to make them work. For example, they don't take fouls into account, which is probably a major reason why LeBron isn't in the Top 10 - because they haven't implemented free throw shooting into their APV models yet. I haven't read it anywhere, but I'm assuming they also haven't been able to fully implement dribbling turnovers into their model either, for example, accidentally stepping out of bounds, the opponent stealing the ball or even something like dribbling/passing the ball off of the opponents foot where play stops but the team retains possession with more time assed to the shot clock (sometimes)

    I'm not a Raptors fan, I was just roaming the internet looking for more information about this stuff and this is one of the best forums I have come across.

    To the person who said that sooner or later we won't even have to play the games to win...that's not even close to accurate. Even once the model is "perfect" or as close to perfect as it can get, its still only an expected value. To those of you who aren't familiar with the concept of Expect Value in statistics, it's simply a summation of all possible [(outcome values)*(their respective probabilities)].

    For example: if there is 5 seconds left on the clock, the warriors are down by one and Steph Curry has the ball with no defender within 10 feet of him, everyone is going to expect him to hit that shot. So his EPV should be something above 1, meaning that the Warriors should win. But what happens if it's that 1% of the time that he misses the shot? The Warriors then lose.

    In order to get accurate expected values, we need a large sample size. And even then, when we use the model to predict, we will run as many simulations as possible. However, when the game is played, it is essentially only one simulation, which means we can see the extremes happen, even if they aren't too "extreme"

    The most famous play that is talked about with this data is the game-winning 3 by Kawhi Leonard against the Cavaliers, although the play that I am most interested in is Ray Allen's 3 pointer in Game 6 of the Finals. Unfortunately, the game was in Miami which means that no SportVU camera captured the moment. But my guess is that the EPV for that whole possession was never close to 3.00 - from LeBron's 3 point attempt, to Bosh's rebound, to Ray back-peddling to the 3 point line and putting up a shot with a not-so-normal form (although the current model may not have taken Ray Allens's form into account). This goes back to the argument of "Clutch Shooting." Needless to say, he hit the shot and told security to "Get those motherfuking ropes off the court."

    Another thing that I thing SportsVU could seriously benefit the players with is form. Being a student with an Ergonomics background, I'm sure these cameras could capture the players form and a quality control algorithm could be coded into the program to notice if a player starts consistently shooting with a form that his atypical to his norm. I remember a few years ago there was a very good free-throw shooter (I want to say it was Jason Kidd) who found himself in a slump and couldn't figure out why. Eventually a video intern noticed that his elbow angle was different from what it used to be, the player changed it and busted his slump. I feel as if this issue could have been solved much earlier with the XY Hoops Group stuff.

    Hope this post wasn't too long for everyone. Either way, there is some stimulating conversation going on in here.

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  8. #26
    Raptors Republic All-Star stooley's Avatar
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    ^ thanks for that post man. it's always nice to read something like that.

  9. #27
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    Quote wwlyle wrote: View Post
    ...I'm not a Raptors fan, I was just roaming the internet looking for more information about this stuff and this is one of the best forums I have come across....
    Come back...and post often. Great stuff in your post and a real addition to this particular thread. Very low AQ (asshole quotient) here but I personally applaud all moves to lower it further.

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