APBRmetrics

[Italian Stallion]

Has anyone ever tried to determine if teams that have played better or worse than usual lately, tend to continue playing that way or whether many of these streaks are just random occurrences?

It seems to me that if you can identify a catalyst for a changed level of play (recent key injury, key player returning from injury, recent trade, coaching change, significant lineup change, a young player that blossoms suddenly etc...) then a change in level of play might be more likely to continue, but absent that it's less clear.

For example, based on their efficiency differential and records for the season, IMHO Miami deserved to be the clear favorite over the Lakers last night because they were home.

However, the Lakers were perceived to be playing at a much high level after the all star break and the Heat at a much lower level. So the Lakers were actually favored.

The thing is, there was no catalyst for thinking either of those teams had somehow changed in a permanent way. It could just as easily have been a random distribution of good play and fortune for the Lakers and vice versa for the Heat.

Any thoughts?

[DSMok1]

Yes. I based my analysis on Bayesian Theory: http://godismyjudgeok.com/DStats/2011/nba-rankings/on-bayesian-predictive-efficiency-rankings/
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[Italian Stallion]

It's going to take me some time to wrap my head around everything there, but it looks like I asked a very timely question and you did a great job studying it. Thank you.

I have been trying to chart each team's efficiency differential adjusted for home/away and schedule strength as a moving average to see if there is a long term trend in either direction as opposed to a sharp temporary change due to a catalyst.

Next year I intend to make clear notations of all injuries and other relevant information.

[Jeff Fogle]

The markets tend to emphasize recent form IS. The public isn't very much involved in those markets right now because of the economy and because they prefer college to pro basketball if they're betting basketball. So, the markets right now consist of oddsmakers posting openers, and professional wagerers taking their shots.

Oddsmakers tend to use Power Ratings, which are just numbers they continually adjust from the gut to reflect how teams are playing right now. (Miami's an 80, wait...they're playing worse lately, I'll drop them to 79...jeez, is it so bad I should move to 78?)

Bettors referred to as "sharps" in the industry come at it from a variety of directions. But, they are generally influenced by recent stuff. They look for the kinds of catalysts you mentioned that trigger changes in form. The guys I know who use Bayesian Priors were surprised at how performances over the last five games or so had better predictive value going forward than larger samples. So, even the "data" people who are surviving in the market have shorter term focuses than you might have thought.

Sharps I'm aware of who preferred the Lakers last night said they did so for the following reasons:

*Miami's defense has really faded lately, suggesting possible fatigue or trouble incorporating their new personnel in a defensive flow. I think defensive efficiency was around 112 the last six games, which is horrible.

*The Lakers looked to have kicked things up into playoff mode lately, which means they'd continue to perform better than their prior norms before the All-Star Break.

*If it went down to the wire, they'd rather have the Lakers in the final minute of a close game than Miami given the Heat's lack of offensive flow late in close games this year.

I agree with you that full season math would have graded Miami as the favorite. But, that was also true vs. Portland, Chicago, Orlando, etc... Miam was a favorite in those games, but hadn't been playing to its full season math. The Lakers had been overachieving their full season math for awhile too.

I guess I disagree with your point that "there was no catalyst for thinking either of those teams had somehow changed in a permanent way." Wearing down defensively could be seen as a catalyst. The Lakers flicking a switch to bring playoff level intensity more consistently could have been seen as a catalyst. Maybe not "permanent." But, in a way that would influence what happened in that particular meeting at that moment in time.

Miami trailed entering the fourth quarter. It was a tie game with 1:30 to go. Miami did execute in the final moments to overachieve market expectations. Miami bettors cashed their tickets...but that was after Miami had failed to do that 8 straight times.

Fun mental exercise to mix math and the markets. So tough to get an accurate snapshot of moving targets though...

[greyberger]

This kind of perspective is appreciated and makes for a great read, even without an active interest in sports betting.

[Mogilny]

[Italian Stallion]

I've been trying to apply everything I've learned in my own studies, here, and elsewhere into wagering on the games this year. I've had very good results....so far (don't want to jinx myself).

This is one of the things I am having a very difficult time incorporating.

The way I am coping with it is to limit my bets to situations where I feel I have an edge on what I believe I can value well and more or less get the other potential pluses "for free".

Relevant to this discussion, if I already like a team and the short term trend is either favorable to them or unfavorable for the opponent, that's a play. That trend either means I have even more the best of it or it means nothing, but it can't be a bad thing.

But if the recent trend is against my team, I simply pass the game because I don't now what it means or how to value it.

I would like to be able to value it better.

The Sixers are a great example. They are playing way better lately than over the course of the entire season. If I liked the Sixers, I'd love the fact that they have been playing better lately, but I won't bet them based on their recent performances because it would not shock me if some of that good play reversed itself just as quickly as it came and for no reason. I've seen that kind of thing repeatedly all season with other teams. It more or less just turned out to be a random run of either good or bad fortune that was getting built into the odds improperly for awhile because so much attention was being paid to the short term.

[Italian Stallion]

After today's dominant win over a fairly hot Memphis team following the victory over LA, am I now supposed to believe that Miami is HOT again or that the previous losing streak was just noise that people were over reacting to.

To me, absent a clear cut catalyst that suggests permanent change this was probably all a bunch of noise.

[Jeff Fogle]

Noise comes from all directions. Miami was 12 of 19 on treys (Bibby 5 for 5). The big three all had very good games (they've been vulnerable whenever one of the three wasn't shooting well). The team was 58% from the floor on all shots. An extreme in the opposite direction of some of their negative extremes.

There may be a danger of looking at it from a "permanent change" catalyst vs. "a bunch of noise" dichotomy. Basketball is a game of constant adjustment. There are likely to be a lot of little temporary changes that make the noise even messier.

Bibby is acquired but doesn't know the offense yet
Bibby isn't a factor and gets left alone outside the arc
Bibby makes a couple of shots and starts really contributing
Bibby goes 5 for 5 on treys
Opponents now start dealing with the threat of Bibby
Bibby deals with the new attention
And so on...

I agree that there are often permanent catalysts that matter (Cleveland becoming irrelevant after losing LeBron is an obvious one that comes to mind). I think there can also be short term catalysts within the "chess on wood" sequences that are meaningful until they're dealt with. Yet, there's also randomness (lol). Part of the market reflects the "essence" of the teams, part reflects estimations of smaller influences (injuries, fatigue, etc...), and some is undoubtedly misreads of randomness.

Can't disagree with looking for permanent catalysts. Wouldn't discount the possibility of temporary catalysts.

Vogel at Indiana inspired a new attitude, and was getting production at fast tempo's. Some players had an argument...everyone's legs got tired...ebb and flow that might look random from the blimp, but seems more logical from reading boxscores and local team media reports...

[Mike G]

[Jeff Fogle]

Agree with you about the Dampier issue Mike G.

Don't think it's right to include LA in the sample in terms of what sharps were thinking before that game was played. The 112 approximation was in the six games before that (and was used as an attempt to try and figure out why the Lakers were favored at Miami).

So...it's SA as the only elite team in the sixpack, and then 1 great game, 2 okay ones, and 3 horrible ones in the sample that would have been influencing the market heading into the LA game.

Two good defensive samples since. Memphis ended up grading very poorly in treys per possession in a little study I put up at hoopdata. Put them behind the eight ball when they fell behind. And, given Miami's struggles to guard the perimeter vs. Orlando and SA, maybe that was an ideal matchup from the Miami defensive perspective. Small sample obviously. Don't want to diminish Miami's dominant win over Memphis. Kind of a harmonic convergence of fluctuations with production and a favorable matchup...combined with their very talented core. Miami's been on quite a yo-yo lately, and the high's are something to behold.

[Italian Stallion]

[Italian Stallion]

[Jeff Fogle]

Agree with much of what you said IS. I think what makes the market so interesting is that it's trying to simultaneously deal with the forest and the trees...or strong signals and noise.

Your initial question about "has anyone tried to determine...?" is at the heart of the buzz of activity in the market. I think most efforts involve looking at both forests and trees. The challenge is finding the right ratio, or weighing the impact of different dynamics (playing a back-to-back at altitude for example). Best of luck with your continuing efforts...

[greyberger]