Wednesday, 2 September 2009

Comment Comment

I received the following comment on my “Nerdy Anorak Elo Stuff” post a couple of days ago:

“I'm sorry, these football ratings systems don't work. One-size-fits-all constants for short and long term form/home team advantage don't work. Ratings have no consideration of team line-ups or team tactics, they might pick up the odd rick in League 2, but the clued up football punter will always trump them and pick up any value. Do yourself a favour Cassini and spend your time on something more fruitful. If you do make it pay I'll give you the money myself...”

Let’s break this down. I'm sorry, these football ratings systems don't work. Back in 1991-92, I used a pencil, a pocket calculator, reams of paper, hours of time and Elo ratings on British football to make a nice profit. Ladbrokes ultimately closed my credit account, which I was quite proud of at the time, and with family and career taking up more time, this was a one-off achievement. So unless this season was for some reason a fluke, is it definitely possible to find a way to use ratings to make money on football.

Football betting, contrary to how it would seem, is certainly not easy. Leaving aside the fringe markets, football has three outcomes. The game results in a Home win, an away win or in a draw - with the draw being a pain in the rear for computing odds! However, with the high liquidity on football, the over-round is minimal, and the potential for finding value should definitely exist.

Ratings have no consideration of team line-ups... The commenter makes the point that a purely objective selection method doesn’t factor in changes in line-up which is very true, and any significant changes in personnel have to be respected. For this reason, games involving Notts County and Manchester City are not being considered for betting purposes until a few games have gone by.

… or team tactics. The second point that an objective system doesn’t consider team tactics is not so valid, at least not for pre-game punts. Unless you are the manager, or somehow have access to such inside information, no one knows what tactics will be used, and tactics are often adjusted depending on how the opposition play, so whether you are a subjective or an objective punter, the possible tactics do not mean that much.

…but the clued up football punter will always trump them and pick up any value. I agree that for in-play betting, the ‘clued-up punter’ may well be able to recognize an advantage, but with thousands of ‘clued-up punters’ out there seeing the same thing, I would disagree that they can necessarily find value. They won’t be able to find an edge because it will be gone - eroded by the deluge of like-minded gamblers.

I would also like to ask how the bookies arrive at their odds. I would imagine that they all crunch the numbers, (what numbers I would like to know) and then sprinkle in a little subjectivity and arrive at the prices they publish. They are protected somewhat by their over-round, but in principle, their methods are not too dissimilar from my own.

Do yourself a favour Cassini and spend your time on something more fruitful. Agreed, there are indeed certainly easier ways to make money on the exchanges, and I focus on those when they are available, but the markets I focus on leave me with plenty of down-time to write boring blog posts and explore other investment possibilities.

Besides, it’s not all about the money. I actually enjoy playing with numbers and ratings and the like and I enjoy the challenge of pitting my wits against others. If I make a few bob, that’s a bonus, and if I lose, it’ll only be loose change.

If you do make it pay I'll give you the money myself… I look forward to receiving your payment. PayPal accepted…

Premier League totals to date (1pt level stake, commission excluded) after 36 matches:

Elo Ratings Only: +7.58 (+21%)

Form Only: +20.22 (+56%)

Power Only: +3.91 (+15%) (from 26 matches)


Pete Nordsted said...

I agree with you Cassini. I used to do these ratings but time constraints have meant that I just do not have the time to keep them going.

I do however look at all of the Premiership, Championship, MLS and live televised matches every week to see if I can find any perceived value.

My methods basically involve looking at how teams have fared in the past against opposition of the same calibre. I also take into account very recent form. And so far this has proved profitable.

I am very much like you in the fact that I love pouring over the statistics and pitting my wits against the rest.

Incidentally and this is a little discussed subject. How do you price up the draw? I personally tend to side on the historical norm.

Anonymous said...

Comment Comment Comment:

Fair enough I suppose the proof will be in the pudding, I do think you skirt over the problems though, a missing Gerrard would make a huge difference to Liverpool's rating and to lesser extent you could apply this to any other player, just look at the volatility of prices on Betfair when team sheets come out. I'm not sure team tactics are that hard to judge either, I've got a pretty good idea how Hull will play at Old Trafford, something a rating system can't do. Good luck anyway but my money is pretty safe ;)

Cassini said...

Pete - I take the draw out of the equation and compare the bookies/excahnges implied probability with my own. (e.g. if a bookie has the three outcomes all at 3.0, the implied probability on each team is 50%).

Anon: "a missing Gerrard would make a huge difference to Liverpool's rating" Agreed, (although I disagree that too many players would have the same impact as a Gerrard). When a top player is missing, the game should be excluded.

The effect of team tactics on the price is overrated. If a team can successfully change tactics and get results against the odds, this will be factored into the rating already. It's nothing to do with judging them - certainly not from a pre-game punting point of view. Each team will start out with the tactics they consider will give them the best chance of a good result.

I'll leave my PayPal account open for you...