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DenButsu
11-08-2010, 03:23 PM
From Fantasy Lounge (http://fantasyloungesports.com/index.php?option=com_content&task=view&id=844&Itemid=1) (and btw, I don't think hoopdata ever got XeFG% up for players):


Roster Inspection: XeFG%
Written by Eno Sarris
Monday, 23 November 2009

The Sabremetric revolution is making its way through basketball. As experienced fantasy baseball players, you may be used to such terms as BABIP and xBABIP. Now its time for fantasy basketball players to get used to eFG% and XeFG%, two concepts that are about to help us define buy low players by mapping out why exactly a player might expect to shoot better, soon.

First, it’s time to explain the simpler stat. Effective Field Goal percentage levels the playing field by giving three-point shooters credit for that extra point they are aiming to score for their team. If a player shoots 33% from three, for example, they’ll score as much as a guy shooting 50% from two. The math is simple. In today’s basketball, a dead-eye shooter from three is worth as much as a bruiser in the middle when it comes to scoring.

But that’s real basketball, you say. What about fantasy basketball? Get to the point.

All right, here we go. On average, the league puts up an eFG% of close to 61% at the rim, 42% from < 10 feet, 40% from 11-15, 39% from 16-23, and 53% from three. We’ve all heard the adage that there’s no worse shot than the long two, and there’s your proof. You want a player that attacks the rim and shoots the three.

Using the actual number of shot attempts from those locations, you can figure out what a player or team SHOULD be shooting! Map how many shots they hoist from each spot and you can guess how effective they should be. Call it XeFG% (expected effective field goal percentage) and go on over to Hoopdata.com to see teams’ XeFG% for this year.

You’ll spot some teams that should be shooting a little better upon first glance. You’ll notice that Charlotte should be shooting better, since they just take threes and go straight to the hoop, but then you should also note that Gerald Wallace trails only Joakim Noah as starters in the percentage of his shots that are blocked (15.1%) despite going to the hoop for eight out of his eleven attempts per game. That includes a block on an impossible 22% of his close shots, too (via 82games.com).

Matt Nolan, in his blog post debuting XeFG%, talks about Chicago as being a team that could expect to shoot worse because they lead the NBA in shots taken from the worse place on the floor. He even goes to defense and talks about how XeFG% plays a role in some of the best defense in the league (hint: they wear green).

The real revolution will hit when they reveal their XeFG% for each player. Then we can do more analysis like my look at the effect Los Angeles has had on Ron Artests’ game that published on RotoExperts.com last week. Here’s the relevant part, excepted:


How about Artest’s offense? Is he still using too many possessions in an inefficient manner? In a word, no. It may not be surprising that, on a team with teammates like Kobe Bryant, Pau Gasol and Andrew Bynum, Artest is willing to defer. He’s putting up the smallest usage rate of his career by far (17.6%). Obviously, this is also reflected in his assist totals, but the offense is also 10.4 points better with him on the court, which betters Ariza’s ‘08-09 numbers. The adjusted numbers show Artest is helping those around him, too (+11 points). There are definitely some sample size issues in this year’s numbers, but Artest betters Ariza in adjusted plus/minus numbers on offense in 2008-2009, too.

How can Artest, the guy who uses too many shots and has a career field goal percentage of 42.2 percent, be great on offense? Well, we already covered one way. He’s giving the ball up to his teammates. But take a look at his broken-down shooting stats, and you’ll also see that he’s taking the fewest shot attempts in the 10-23 foot range this year than in the past four years (two per game this year, closer to five per game the last three years). Shots in that range traditionally produce the worst shooting percentage on the floor – the long two is the least efficient shot in basketball. Artest has cut down on these poor shots while still taking the same amount of shots at the rim (around four) and from three (almost five). So playing on the Lakers has allowed Artest to reduce his most inefficient parts of his games while emphasizing the best parts of his offensive game.

Once HoopData gets the XeFG% per player up, expect an effective article on field goal percentage and some buy-low and sell-high players. Consider this a teaser.

I have no idea how highly regarded this stat is in the statistical community, but it seems sensible to me.

ChiSox219
11-09-2010, 01:27 AM
I noticed this stat on Hoopdata last year but I'm still not quite sure what to think of it.

From the article, you see an immediate flaw; the Bulls eFG% is expected to go down because they take so many long twos. However, with Boozer due back in about a month, I'd guess the Bulls eFG% rises, not only because of his scoring effectiveness in the paint but also his ability to pass the ball from either the low post or high post.

"long two's" are the worst shot. However, let's use Joakim Noah as example. Noah was shooting 73% from 16-23 feet coming into today on 2.2 attempts. I would rather have him take that wide open 18 footer than a contested shot at the basket.

Basically, I don't know how you can separate contested vs uncontested shot because you would need to do so to make this stat useful.

daleja424
11-09-2010, 10:59 AM
I disagree ChiSox. It all averages out for everyone. If you are looking at a comparison of players using any stat do we ever break it up like that? We don't look at rebounding rate in traffic vs uncontested rebounds... we don't look at assists for uncontested shots vs contested ones. It is an understood part of the game that some shots are challenged and some are not for all players.

As for your point on the Bulls... again, I disagree. There will come a point in the year that, like every other team, those shots will not be falling at a good clip...and that eFG% will come back to earth. You also fail to realize that Taj Gibson is playing OUT OF IS MIND RIGHT NOW. He is shooting 63% from the field in 30 mpg. When Boozer comes back he is going to get a majority of those 11 looks Gibson is getting right now... and he will not be shooting at a 63% clip.

Overall, without looking at the specifics... law of averages will bring that eFG% down. Right now the Bulls have several players playing at career levels and a lot of guys that are playing insanely efficient (Deng at 43% from the 3, Gibson, Noah, Korver, etc).

I find it extremely hard to believe that the Bulls will be able to maintain this level of efficiency, and certainly not be able to increase it.

For comparison purposes...last year the Bulls were near last in the league in efficiency @ 47.72% eFG and so far this year they are nearly 5% better so far and near the league lead. I find it far more likely that they have gotten off to a hot start, as opposed to them just being insanely more efficient in the span of one offseason.

ChiSox219
11-09-2010, 03:00 PM
I disagree ChiSox. It all averages out for everyone. If you are looking at a comparison of players using any stat do we ever break it up like that? We don't look at rebounding rate in traffic vs uncontested rebounds... we don't look at assists for uncontested shots vs contested ones. It is an understood part of the game that some shots are challenged and some are not for all players.

We are talking about XeFG%, so yes it is very important to differentiate the looks if you expect to be able to predict anything.



As for your point on the Bulls... again, I disagree. There will come a point in the year that, like every other team, those shots will not be falling at a good clip...and that eFG% will come back to earth. You also fail to realize that Taj Gibson is playing OUT OF IS MIND RIGHT NOW. He is shooting 63% from the field in 30 mpg. When Boozer comes back he is going to get a majority of those 11 looks Gibson is getting right now... and he will not be shooting at a 63% clip.

Again, XeFG%, we are talking about shot selections here. The Bulls XeFG% is low not because the Bulls are shooting so well, but because of where they are shooting from. When Boozer comes back, we'll have more attempts in the paint and more from beyond the arc. Less from mid-range because we won't be asking guys to create who aren't capable.



Overall, without looking at the specifics... law of averages will bring that eFG% down. Right now the Bulls have several players playing at career levels and a lot of guys that are playing insanely efficient (Deng at 43% from the 3, Gibson, Noah, Korver, etc).

Sure the numbers are going to change. But with defenses so focused on stopping Rose, guys like Gibson get nothing but wide open 15 footers. Deng is getting the most open looks from downtown in his career (and it's not like he was a bad 3pt shooter coming into the season).

I'd guess at some point defenses start contesting Noah's jumper, but again, do try to stop Noah at 20 feet or Rose at 2 feet?

Anyways, our primary scorer is going to shot higher than .460 eFG% and Boozer comes in with a career .541 eFG%.



I find it extremely hard to believe that the Bulls will be able to maintain this level of efficiency, and certainly not be able to increase it.

Well, the team is talented and has a proper coach, I guess we'll have to wait and see.



For comparison purposes...last year the Bulls were near last in the league in efficiency @ 47.72% eFG and so far this year they are nearly 5% better so far and near the league lead. I find it far more likely that they have gotten off to a hot start, as opposed to them just being insanely more efficient in the span of one offseason.

Why are you comparing this year's team to last year's team? The Heat eFG% is .518, way up from last year's .496, that means they must be hot and they will come back to Earth, right?

daleja424
11-10-2010, 12:16 PM
the heat dont have essentially the exact same team as a year ago...

the bulls have added Korver and Brewer and lost Hinrich... those are the main differences in your rotation right now... and i dont think that alone accounts for a 50 point spike in eFG... i think it is also a matter of your guys making shots right now that will not fall at that rate all year. but we can certainly disagree on that.

ChiSox219
11-10-2010, 06:16 PM
the heat dont have essentially the exact same team as a year ago...

the bulls have added Korver and Brewer and lost Hinrich... those are the main differences in your rotation right now... and i dont think that alone accounts for a 50 point spike in eFG... i think it is also a matter of your guys making shots right now that will not fall at that rate all year. but we can certainly disagree on that.

Besides Korver, Bogans, Brewer, Watson, Asik (half the rotation) the Bulls went from Vinny Del Negro's 1 play offense to Thibs' diversified attack.

Big difference between this year's team and last years.