Saturday, July 28, 2012

Today's Games - Relaunched

Coffee cup iconThe Today's Games feature of this site has now been relaunched for Major League Baseball.  I had originally published this during the 2011-2012 NBA season.


The purpose of this feature is to, effectively, "predict a prediction".  The main feature of this site is the betting market power rankings, which are my attempt to reverse engineer what the betting market thinks about team and pitcher strength.  What Todays' Games does is then take those rankings and try to predict how the betting market will set the moneylines and run totals for each day's games.

The goal here is to look for discrepancies between my prediction of the betting numbers and what they actually turned out to be.  If my modeling perfectly captured how the betting market "thinks", then any discrepancy in the predictions would be due to new, late breaking information.  During the NBA season, I found that these discrepancies were usually good indicators of key players either sitting out due to injury, or a key player returning from injury after a long absence.

Sunday, July 22, 2012

Rankings Now Adjusted for Ballpark

In this post on ball park adjustments, I derived how the betting markets adjust moneylines and run totals to account for where the game is being played.  From that analysis, I found that home field advantage is relatively constant across teams (it's worth about a 0.4 run advantage).  In contrast, I found that the betting run total shows significant variation from ballpark to ballpark.  As it is common knowledge that some parks are hitter friendly (e.g. Rangers Stadium) and some are pitcher friendly (e.g. Petco Park), it's not surprising that the betting market has factored that knowledge in.

The purpose of this post is to announce that the team rankings and pitcher rankings, as well as The Ticker features of this site, now account for these ballpark adjustments. You can find the adjustments themselves here.  I have based them on an average of the 2009-2011 seasons.  Here is an explanation of the fields:

Sunday, July 15, 2012

Ballpark Adjustments and Home Field Advantage

Shibe Park 1943
Philadelphia's Shibe Park
The left field fence had the following message to fans:
"WARNING: Persons throwing bottles or other
missiles will be arrested and prosecuted"
The purpose of this post is to investigate to what extent the betting market factors in ballpark when setting moneylines and run totals.  What I found is that there are clear ballpark adjustments on the run total side.  However, when it comes to moneylines and win probability, betting line home field advantage does not vary significantly from team to team, with most teams getting around a 0.4 run advantage and an expected win probability of 54% when playing a team of comparable strength.

Why Ballpark Adjustments?

Baseball seems unique among the major sports in that teams are allowed considerable leeway when designing their parks.  An NBA team isn't permitted draw the three point line at 22 feet on the left corner, instead of the standard 23 feet 9 inches, or shrink the size of their backboard (maybe they should?).  Not so with baseball, with outfields, home run fences, and power alleys that vary from ballpark to ballpark.  Add to that the impact that weather and climate can have on how far a baseball travels and you end up with some significant variations in runs scored, depending on the venue.

Sunday, July 8, 2012

The Ticker - Relaunched for MLB

Over the past two weeks I have focused on extending my betting market ranking system to major league baseball. My first post focused on methodology. My second post on the topic showed the team rankings that resulted from that methodology. My most recent post showed how the methodology could be used to rank starting pitchers as well as teams.

The purpose of this post is to announce a relaunch of The Ticker, a feature I had previously published on this site for the 2011-2012 NBA season. The idea behind the ticker is pretty much the same as a normal stock ticker: to provide realtime information on what the market is thinking. However, where sites like Google Finance can just report stock prices over time directly, to do the same for sports betting requires some mathematical manipulation on my part.

Sunday, July 1, 2012

MLB Pitcher Rankings

Last weekend, I published a two-part post on ranking major league baseball teams based on betting market information (moneylines and totals).  Part one covered methodology and part two covered the actual rankings.  

As indicated in part two, I have created a set of pitcher rankings that are also derived from betting market information. Starting pitchers require several days of rest between games, so each major league baseball team is actually more like 4 or 5 distinct teams, and my rankings effectively treat them as such.  Although that complicates the ranking methodology somewhat, it allows me to determine how the betting market evaluates the strength of each pitcher individually.