#Spursy luck… and its abundance (so far)

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Warning: what follows involves trying to generalise and abstract the season to date. If you think that’s impossible, skip this thread. Nothing below proves anything, but it suggests a lot.

For a few decades now, baseball has made use of the ‘Pythagorean expectation’, which estimates how many games a baseball team ‘should have’ won based on how many runs they scored and how many they allowed. Teams that win more games than they should have are considered ‘lucky’, and those that lost more are considered ‘unlucky’.

On the one hand, luck is probably best considered to be a random, uncontrollable fluctuation. It’s possible, for example, to roll a six with a single die four times in a row, but considering doing so has a probability of about .08%, successfully doing so can only be considered extremely lucky. On the other hand, it may be that teams are capable of ‘producing’ their own luck. More on that below.

Because of the presence of draws in football, matching the Pythagorean expectation to predict how many points a club ‘should’ score in a season based on how many goals they score and let in is a bit more complex, but, taking into account recent season performances, Martin Eastwood of Pena.lt/y has come up with an empirically deduced formula for an ‘MPE’ that calculates an expected point total for a club in the league based on goals scored and allowed. According to Eastwood, his formula has an MSE of 4.04, which means that, on average, the actual, real world number of points scored by a club tends to be about four points off (one way or the other) from what the predictor estimates. In terms of qualifying for fourth place, a difference of four points is a lot. But trying to rein in randomness in a sport like football is astonishingly tricky, and getting that error down to 4 is an impressive feat.

So how do Spurs fare with the MPE? Before showing the graph, there are a few considerations. First, many posters on the forum throughout the AVB reign complained about how ‘lucky’ we had been, winning 1–0 off lucky penalties (in contrast to last season’s dearth of penalties that I discussed). These lucky wins were the bare minimum route to three points. Our losses to West Ham, City, and Liverpool suggested what would happen once AVB’s luck ‘ran out’, so it was imperative to sack AVB to bring in a manager who would not be riding his luck off fluky 1–0 (Soldado, pen) matches.

Second, however, other posters have argued that Tim Sherwood has been the lucky one, getting a bunch of players back from injury just in time and reaping the benefits of a comparatively easier schedule. Facing City at home is a less terrifying proposition, for example, than going to the Etihad.

So, again, how do Spurs fare? Well, here’s the chart (calculations only done from the sixth match to reduce noise):
Sn5E0t7.png

Most notable is the fact that we have scored far more points in the real world than we ‘should’ have. Currently, Spurs can attribute about 11.5 points strictly to luck, considering how little we have been scoring and how many goals we have been conceding. From the MPE, we should be expecting to to finish the season on about 54 points, yet we’re almost at that level now.

It’s clear, from looking at the expected season end (green), that both defeats to West Ham and City hurt our expected total badly. Since the 0–3 was early in the season, the subsequent two wins helped erase that fall, but the massacre in Manchester has taken the rest of the season to erase (not helped by a certain, job-costing 1–5 defeat). We haven’t lost a lot, but when we have, we’ve typically gotten absolutely pounded, which is, perversely, lucky. If City had beaten us 1–0 and those other five goals had been distributed across other matches, we’d probably have fewer points in real life. Better to lose 6–0 once than six times 1–0 and all that…

But what’s interesting is that we seem to have been getting luckier as the season has gone on. After City, we had seven more points than we should have. Now it’s almost 12 (though it has been falling since our win against Everton). Falling results are obvious: we lose/draw matches or tonk other sides (like Newcastle) to make our goal tallies more representative of the number of points we actually do have. But results that widen the gap are confusing: either we get tonked (so the predictor has pity on us) or we win ‘luckily’.
kiHCfj8.png

Under AVB, it looks like we ended up having ten extra ‘lucky’ points, while Sherwood has only brought in another point. That would suggest that, perhaps, Sherwood is getting results in line with Spurs’ skill, while AVB was riding Spurs’ luck. But the chart above is a bit unfair, since it adds the preëxisting goals for and against that we had under AVB to Sherwood’s account. It’s a kind of handicap. If we look only at the matches since Sherwood has been in charge, we see:
nYZpQRy.png

Once Sherwood has a blank slate in terms of MPE, then he’s now accumulated seven extra ‘lucky’ points in 11 matches. After 11 matches, AVB had only 2 ‘lucky’ points. So that suggests that Sherwood has been luckier than AVB so far this season. The ‘Soldado pen, lucky AVB’ crowd can’t have expected that, right?

But then there’s the question of ‘manufacturing’ luck alluded to above. On the one hand, luck should be random… It’s possible to have four instances of good luck in a row, but in the long run, it should even out. Maybe Sherwood has some kind of gift to grind out wins when matches are tight. Perhaps that’s the result of his man management alluded to by the article that suggested today that Sherwood could stick around even if we don’t get fourth. But when I consider our performance at Carrow Road and look at the table as a whole, sorted by MPE:
Vfa8dxm.png

I think to myself, ‘Yeah, maybe eighth sounds about right.’
 
8th would be an achievement at this rate and probably deserved all things considered
 
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Lovely analysis @ Éperons Éperons ... I know this sort of stuff isn't everyone's cup of tea, but I've gotta say, good job.

Have to say though, the fact that our MPE jumps from 2 to 7 when we got hit for 6 at the Etihad does seem very counterintuitive. I can understand why it's jumped... but it does seem odd!
 
I am guessing you do stats as part of your day job. Of course though 'the harder you practice the luckier you are'.
No chance on the day job thing. I'm actually pretty bad at stats—what's key here is that the calculation is super easy. It's just a question if being able to look at what's in front of you while trying to remove as much bias (selection, recency, sexual attraction to mustelids, etc) as possible.

Manufacturing luck is hypothetically possible. In baseball, the easiest way to manufacture luck is by having a crack bullpen—one-run games are considered to be 50/50 affairs (teams are expected to win as many one-run games as they lose), but having a great bullpen helps you keep a one-run lead from turning into a one-run deficit. Manufactured luck.

For obvious reasons, it's much trickier to do this with football, since draws exist and since one-goal wins make up such a huge part of the pie. That means that randomness plays an enormous role in the outcomes of matches—I argued with Sammy last year, for example, that a team finishing around fifth should expect to lose about five matches a season at home (iirc). Hence I wasn't shocked by our losses to the likes of WBA, which many took as evidence that it was time to start calling for AVB's head. So if we were about fifth quality (and I think we were), it made sense that, somewhere, points would get dropped at home. It was what fifth place teams did.

But third place teams didn't. They could weather the randomness better and drop fewer points. Something about them—wages, manager—generated luck. It's just hilariously tough to figure out what that is and how to harness it.

My op was running long, so I didn't calculate the MPE of Spurs over the past few seasons. Partly that's ok since the constants (and exponents) of the MPE change over time. But partly also since the guy at Pena.lt/y wrote that Spurs traditionally beat their MPE. That doesn't square with my recollection of last season, where our shot conversion rate and save rate suggested we were astonishingly unlucky. And we were unlucky that our points haul wasn't enough for fourth, but there's little we could do about that! But if according to MPE Spurs have strung together seasons of lucky points, then maybe we are producing our own magic somehow...

If that's the case, that we have been punching above our weight all this time, then maybe @ Flav Flav is right and we should keep our nuts down and start remembering the mid-table days.

I'm skeptical, though, since I'm an optimist, paradoxical as that may sound!
 
I just about see how it works for baseball (I know nothing about baseball). It is Kinda like entropy, In that you can figure out 'how spontaneous' something is. Interestingly according to the second law things are getting more 'random' I believe.
Anyway back on topic, as you alluded to in football 1-0s are more 'bread and butter'. I don't know but I think there might be bias by using this as predictive variable. Having said that, we won a few games with a penalties and what some people would call a lucky break.
 
I don't know but I think there might be bias by using this as predictive variable. Having said that, we won a few games with a penalties and what some people would call a lucky break.
You mean it might be biased to build a mathematical relationship between goals for and goals against that can reasonably accurately predict how many points a team scores? I don't think so… I think the three are very, very correlated, and the two literally cause the other. And the equation is very simple:

MPE = (( GF^x ) / ( GF^y + GA^z )) * c * GP

[x, y, z, and c are empirically derived constants]

Why or why not a team scores goals, IMO, is more complex a question than why or why not a team wins matches, since the latter is so dependent on the former. So I don't really see a lot of spae for bias here.
 
Is this thread meant to make Monday morning more bearable afterwhatever THAT was yesterday??

Here's an equation for you all....

Liverpool+Suarez{Rodgers}=CL
Tottenham-Bale+€€>Playersx7{-AVB}=SHAMBLES!

The gauntlet of smug I'm having to currently endure from closet Gooners who clearly have some sort of Karma immunity is as STAGGERING as it is SICKENING....
And right now, it's all Spurs' self-inflicted fault!!!
 
Bit irrelevant this comment but i'm REALLY looking forward to Levy's annual closing statement at the last game of the season, I wonder how he might try and weasel any positives out of the performance of the playing staff this season.
 
8th should be our target once 4th is out of reach.
The thought of another season of the ropa league makes me sad.

Nah, next season is the one to be in it. You get a big trophy with a 'permit one entry' ticket to the CL group stages:

http://www.bbc.co.uk/sport/0/football/22640095

Next season also sees a rule change that would have gotten us CL entry two seasons ago (Chelsea would have got a 5th spot rather than taking our place). Bah.

@ Éperons Éperons ... excellent job fella and pretty confirms what I've been feeling for most of the season. Actually, both this and last season we've been sitting higher than we should have been given our performances.
 
Actually, both this and last season we've been sitting higher than we should have been given our performances.
Here's the table from last year:
77MBP7j.png

Those 13 supplemental, 'lucky' points that Man U scored? Maybe that's the Fergie effect. I'm surprised that Liverpool was so comparatively unlucky. But look also at that tight fight at the top!

But, of course, there we are, with eight extra points. Maybe that's the Bale effect.

How about over the past decade? How have Spurs done?
yG5zu4J.png

That the average over a decade is .94 shows that luck evens out in the long run. Our Bale effect last season was basically canceled out by whatever malaise (or just bad luck) overshadowed our League Cup season.
 
Nah, next season is the one to be in it. You get a big trophy with a 'permit one entry' ticket to the CL group stages:

http://www.bbc.co.uk/sport/0/football/22640095

Next season also sees a rule change that would have gotten us CL entry two seasons ago (Chelsea would have got a 5th spot rather than taking our place). Bah.

@ Éperons Éperons ... excellent job fella and pretty confirms what I've been feeling for most of the season. Actually, both this and last season we've been sitting higher than we should have been given our performances.

1 ticket. pretty tight, can't even take a mate.
 
You mean it might be biased to build a mathematical relationship between goals for and goals against that can reasonably accurately predict how many points a team scores? I don't think so… I think the three are very, very correlated, and the two literally cause the other. And the equation is very simple:

MPE = (( GF^x ) / ( GF^y + GA^z )) * c * GP

[x, y, z, and c are empirically derived constants]

Why or why not a team scores goals, IMO, is more complex a question than why or why not a team wins matches, since the latter is so dependent on the former. So I don't really see a lot of spae for bias here.
Not always surely... The old tactics of we will score one then shut up shop. Or the the Italian idea of not winning more than 3-0 to show respect. They are linked but does it not overemphasis goal difference to wins? I mean it is biased against teams who win games by small margins ;)
anyway you are right it is a predictor; If you score more goals and concede less you will win more matches (most of the time).
 
Not always surely... The old tactics of we will score one then shut up shop. Or the the Italian idea of not winning more than 3-0 to show respect. They are linked but does it not overemphasis goal difference to wins?
The genius of the idea is that it is actually not related just on goal difference, but, rather, a relationship between goal difference and goals scored. In order to win, you have to score more goals, but there's also a relationship between how many goals you score and concede. Imagine four clubs. Each got 54 points on the season from 14 W, 12 D, 12 L. But one did it all with 1–0/1–1/0–1 matches, another with 4–3/4–4/3–4 matches, and the last with 4–0/0–0/0–1 and 1–0/0–0/0–4 matches. How do their MPEs match up?
Bypdfo2.png

The first two teams, with the tight GDs, match rather closely the actual number of points they got. If they're a little bit lucky, it's because despite playing with fire (one-goal wins), they managed two more wins than draws or losses. The third club is considered massively unlucky in that they weren't able to maintain that stomping level of class that led to those 4–0 wins. A couple of those 0–0 draws should've been wins. And a couple of those losses should've been draws. Just imagine in your head a club that has a GD of 44 but manages 54 points on the season. Very, very weird, no? On the other hand, the fluky winners but heavy losers… well this is starting to look a little #spursy, no? Getting beaten 12 times 0–4 yet reeling off 54 points? Surely that feels like a really, really lucky club.

So as we see with the slightly ludicrous examples, goal difference clearly plays a role. But so do the goal totals.
 
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