Layups: Hollinger’s Forecasts Are Here! (2010-11 Edition)
Posted by Neil Paine on September 27, 2010
The equivalent of Christmas morning amongst hoops stat-wonks, it's the annual unveiling of John Hollinger's NBA previews over at ESPN. And I'm sure the player comments are not far behind, either... Unfortunately, people who aren't ESPN "Insiders" don't seem to be able to access JH's stuff, which is sad -- but I guess the man has to make a living, just like the rest of us. And for those lucky enough to have Insider, enjoy.
September 27th, 2010 at 3:55 pm
No big surprise, he picks the Heat to win it all. Hollinger over-emphasizes PER in my opinion (probably because he created it) and since 3 of the top 4 in PER last season are now on the Heat he had to pick them.
While I do agree that PER has merit we are missing a few key points
1) A dominant defense leads to a better chance at winning a title than a dominant offense (all else being the same)
2) PER is basically an offensive stat (it does attempt to quantify defense with steals and blocks but doesn't contemplate solid core defensive abilities a-la Shane Battier or Bruce Bowen)
3) Match-ups do matter (especially size)! Look at the Cavs being dominated by Orlando solely due to the inability guard Dwight Howard two years ago. Looks at the Lakers rebounding dominance over the Celtics in game 7 when Perkins was out that helped to win a game that had no business winning with their poor shooting.
I think the Lakers will win it again because they have a dominant defense (especially when healthy) and they have the perfect match-ups to battle the heat. They have a mismatch on the front line with the size and skills of Gasol, Bynum, and Odom that the Heat can't come close to matching and they have three of the top perimeter defenders in Artest, Bryant, and Barnes to match up against Lebron and Wade.
September 27th, 2010 at 6:14 pm
I still have no idea how PER is calculated or what it is based upon. I don't know what weights are given to what stats and, more importantly, why. For instance, I know the guys at PFR argue on behalf of their stats because of the correlation between their weights and victories. They weigh most strongly that which correlates most strongly with wins. Makes sense. What is PER based on? I've tried to read the write-up on ESPN but it didn't really make it any clearer.
September 27th, 2010 at 7:23 pm
PER explanation
September 27th, 2010 at 8:19 pm
DAMN, when in the H*LL did matt "I beat my wife" barnes become a top defender? I must have been on mars without an oxygen tank when that happened.
September 27th, 2010 at 9:05 pm
Re: #2 - I wouldn't get too hung up on PER when reading Hollinger's stuff. All of the criticisms Walter mentioned are valid, and JH does frequently refer to it, but it's possible to appreciate his previews and player comments while still taking PER with a grain of salt. Speaking for myself, I almost never use PER at all, but I value the non-PER content of what he writes.
September 27th, 2010 at 10:16 pm
Chuck-
I understand all that. But the numbers themselves are not explained. At least not in a way that I get.
Neil-
I agree. I still read JH, but I struggle with PER. I think he sometimes offers some really great insight into the game. But sometimes he seems to be number-heavy for the sake of it, and ends up muddling around.
September 28th, 2010 at 7:43 am
Game Score is the simplified metric Hollinger has thrown out there that emulates PER to some extent. From http://www.nbastuffer.com
Game Score Formula =(Points)+0.4*(Field Goals Made)+0.7*(Offensive Rebounds)+0.3*(Defensive rebounds)+(Steals)+0.7*(Assists)+0.7*(Blocked Shots)- 0.7*(Field Goal Attempts)-0.4*(Free Throws Missed) - 0.4*(Personal Fouls)-(Turnovers)
September 28th, 2010 at 8:59 am
Right, the weights are basically a more evolved version of what Tendex had in the early 90s. Give a somewhat arbitrary positive weight to "good stuff", a somewhat arbitrary negative weight to "bad stuff", and add everything up. The only different wrinkle with PER is that it adjusts for pace and is scaled such that the NBA average is always 15. In essence, it's a dimensionless quantity, with an easy-to-understand scale, that correlates well with offensive rating at the team level (which doesn't necessarily mean it correlates well with individual offensive impact) and poorly with defensive rating at the team level. I don't think it claims to be much more, although Hollinger does sometimes treat it as though it were a more complete metric.
September 28th, 2010 at 9:36 pm
Thanks, Neil. The "somewhat arbitrary" aspect of it is what gets me. I get that it's hard to arrive at anything 100% definitive, but we certainly ought to try. And, as you point out, my biggest complaint is when someone purports a stat to be something other than it is. I get that every stat has it's strengths and weaknesses, but as long as we are clear about that and use stats where they are strong and not where they are weak, I'm willing to entertain just about anything. But Hollinger often acts as if PER is the end-all, be-all, and whatever it says to be true is true (even with his own admitted caveat about the defensive aspect). Now, I suppose there may be more rigorous analysis behind his conclusions that he doesn't put into every column for the sake of his audience (he does write for ESPN, afterall). But it's still hard to make much of PER when it seems like a mysterious number plucked out of no where.
I do think his contributions with regards to pace factor have been very important. Must give credit where credit is due.
October 3rd, 2010 at 2:19 pm
PER is worthless and any predictions that use it is therefore worthless as well. All PER does is reward scoring, whether or not is efficient. Look at the top 10 performers in PER and look at the top in scoring average and you will see very similar (not identical) lists. The only advanced stat that actually (and accurately) predics wins, baring injury to key players, is Wins Produced (WP) by Dave Berri. Search wages of wins in google and you will be convinced.
October 3rd, 2010 at 3:46 pm
I feel obliged to point out, Leroy, that Wins Produced also has a number of well-known, extremely serious flaws:
http://sonicscentral.com/apbrmetrics/viewtopic.php?t=877
http://www.sonicscentral.com/apbrmetrics/viewtopic.php?p=18975
http://sonicscentral.com/apbrmetrics/viewtopic.php?p=17287#17287
http://sonicscentral.com/apbrmetrics/viewtopic.php?t=1589
http://sonicscentral.com/apbrmetrics/viewtopic.php?p=13946#13946
Et cetera, et cetera.
October 3rd, 2010 at 5:51 pm
With every advanced stat there are problems. Wins Produced is not different. What I am propsing is that, when you put box score stats into wins produced for any random team in the past you will get within 2 wins or so of what the team actually produced. Dan Rosenbaum and you guys make great points about the weaknesses of WP, but at the end of the day it predicts. That was never denied in any of the links you kindly provided.
Don't think I'm one those that are a slave to any one system. But WP has helped me pull off some neat party tricks.
October 4th, 2010 at 9:57 am
All that means is that team point differential can predict team performance within +/- 2 wins. There's a team adjustment that makes sure WP matches up with wins predicted by pt. differential, but that doesn't necessarily say anything about the validity of the metric.
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