Web Science and Digital Libraries Research Group

We are halfway through the 2013 NFL season and it is time for our WSDL mid-season rankings. Both conferences have one winless team, Jacksonville in the AFC and Tampa Bay in the NFC.  The NFC is looking rather lackluster this year with no standout teams so far. The NFC East teams in particular need to get their acts together. The AFC appears to be dominating the League with  a number of teams that are performing quite well. Two teams that show up on the top of every power ranking list are the Denver Broncos and the Kansas City Chiefs. Kansas City has a great defense, using our efficiency ratings they are rated as the fifth best defense in the league. However a good defense will only get you so far when your offense is ranked at 27th out of 32. Denver on the other hand has the highest ranked offense in our system with a lot of that on Peyton Mannings shoulders. A good passing offense correlates quite well with a team that wins games. Here is where our ranking system rates e...

The NFL salary cap for 2013 has been calculated to be about $123 million. All NFL teams must be in compliance with the salary cap by March 12th when the new league year starts. March 12th also marks the start of the free agent market in the NFL. Teams that are over the salary cap must let some players go and teams that are under the salary cap are looking to add new players to their rosters. The process sounds simple on the surface but in reality it becomes confusing rather quickly. Many teams routinely exceed the salary cap by manipulating contracts. The Pittsburgh Steelers were about $14 million over the cap until they modified Ben Roethlisberger's contract and changed most of his pay into a signing bonus. Signing bonuses can be amortized over the life of a contract. Instead of receiving an $18 million dollar salary, the player gets a $2 million dollar salary and a $16 million dollar bonus. The bonus will be divided by the number of years in the contract and thus reduce the i...

The NFL Conference Championship games are this weekend and just one game separates the four remaining teams from Super Bowl XLVII. If you ignore the vapidity of the Te'o coverage, there is much discussion of how the loss of Rob Gronkowski will impact the performance of the Patriots this weekend. Aaron Hernandez should perform admirably and the entire team should be able to make up the difference and triumph. For our predictions we run a number of different types of algorithms in our research and compare the outputs. The three main algorithms that have consistently had the best performance are a Support Vector Model (SVM), a Multilayer Perceptron Neural Network, and a ranking algorithm. All three algorithms sided with the favorites. The SVM gives us a binary output, winner or loser. There is nothing in between. The SVM chose San Francisco and New England. The Neural Network output is a continuous variable that is supposed to be the margin of victory. A positive score fa...

For the NFL Divisonal playoff week the predictions for all of our algorithms are in agreement. For our predictions we run a number of different types of algorithms in our research and compare the outputs. The three main algorithms that have consistently had the best performance are a Support Vector Model (SVM), a Multilayer Perceptron Neural Network, and a ranking algorithm. All three algorithms sided with the favorites except for Atlanta. All three picked Seattle for the upset. All season long our algorithms have consistently shown that Atlanta is over-rated. Yes they have won most of their games this season but they have had the easiest strength of schedule this year out of the all of the NFL teams. ESPN's adjusted strength of schedule shows that Atlanta has had an easy season. Big Lead Sports states that not only was Atlanta's season easy but it was respectively the easiest season for any NFL team in a number of years. Most of our algorithms take the strength of sched...

The wildcard week of the playoffs is upon us. The numbers were crunched and the results were rather predictable. In three of the games the home is the favorite to win for both the Support Vector Model (SVM) and the PageRank model. For the fourth game the Seahawks were chosen by both the SVM and the PageRank model.  The SVM gives us a binary result so there is no degree or way to judge how close of a game it may be. Our numbers indicate that the Redskins Seahawks game is going to be close and probably a low scoring game. Both teams like to run the ball but the Seahawks defense has performed better that the Redskins this year. What my be interesting is that the Seahawks are a 2 to 3 point favorite and they are the visiting team. Our previous research has shown that home team underdogs are often a good bet to cover the spread. Vergin and Sosik found that not only has the home underdog been viable in some years but that the effect was more pronounced on nationally televised games...

It was the first week of the 2007 National Football League (NFL) season. After waiting all summer for the NFL season to begin, the fans were rabid with anticipation. The airwaves were filled with sportscasters debating the prospects of teams from both conferences and how they would perform. Of particular interest was the New England Patriots. They had two starters out with injuries and their star receiver, Randy Moss, was questionable for the game. New England was playing against the NY Jets and their simmering rivalry add heat to the fire. Many of the sportscasters were lining up with the Jets and Vegas was favoring the Jets with a 6 point line at home. When betting opened for the game the action on the Patriots was heavy. The shear volume of bets place on New England to win forced the sportsbooks to move the spread in an attempt to equalize betting on both sides. Eventually the line moved all  of the way to New England being a seven point favorite by game time. New England ...

The NFL Playoffs are only a few weeks away. With the end of the regular season in sight there are a few trends that subtlety change the game. One of the trends is the weather. Tennessee is playing at Green Bay and snow is in the forecast. Another end of the season trend is displayed by teams that have clinched playoff positions. They rest their starting lineup and play backup players. That is more of a week 17 phenomenon but with Atlanta and Houston both at 12-2 for the season they may play some non-starters during the game. This ranking system is based on team performance and does not take trends like the weather into account. Our ranking system is based on Google's PageRank algorithm.It is explained in some detail in past posts . A directed graph is created to represent the current years season. Each team is represented by a node in the graph. For every game played a directed edge is created from the loser pointing to the winner and it is weighted by the Margin of Victo...

After running the R script for the week 8 rankings, the first thing that struck my mind was the disparity in the size of the nodes between the AFC on the left side of our graph and the NFC on the right side. Two weeks ago we wrote that the NFC West has been dominant so far this year. The NFC West has the best combined record and their aggregate point differential puts others to shame.  However it is not just the West division but the entire NFC conference has dominated and out-performed the AFC conference at every turn. CBS Sports rates the NFC as head and shoulders above the AFC this year. Our ranking system is based on Google's PageRank algorithm. It is explained in some detail in past posts . A directed graph is created to represent the current years season. Each team is represented by a node in the graph. For every game played a directed edge is created from the loser pointing to the winner and it is weighted by the Margin of Victory.  In the Pagerank m...

It is now five weeks into the 2012 season and the season is starting to come into focus. The topic of many online discussions is this years performance of the NFC West division compared to last year. The NFC West is one of the best performing divisions so far this year, which is a far cry from last year. They are certainly doing well in our ranking system. Our ranking system is based on Google's PageRank algorithm.It is explained in some detail in past posts . A directed graph is created to represent the current years season. Each team is represented by a node in the graph. For every game played a directed edge is created from the loser pointing to the winner and it is weighted by the Margin of Victory.  In the Pagerank model each link from a webpage i to webpage j causes webpage i to give some of its own Pagerank to webpage j .  This is often characterized as webpage i voting for webpage j . In our system the losing team essentially votes for the winning team with...

For the first three weeks of the 2012 NFL season, replacement officials have refereed the games due to an ongoing labor dispute between the referees and the NFL. Every fan of a team that has been on the losing side of a call has voiced their opinion on the abilities of the replacement referees. Even Jon Stewart had something to say about the labor dispute . This past Monday night during the Seahawks - Packers game, a controversial call essentially determined the winner of the game. This call was the powder keg that blew open the dam of angry recriminations and complaints directed at the replacement referee s and the NFL. This was somewhat amusing to me as the people complaining seem to forget about all of the mistakes the regular referees appeared to make in all of the previous years. In 2008 one of the best referees in the NFL, Ed Hochuli made a rather horrendous call . I have to give him respect for owning up to it and apologizing. NFL fans have always complained about the offic...

So far this year all three of the prediction algorithms are 68% correct straight up. This is better than the predictions of most of the NFL "experts" such as the guys at ESPN . Last year we ended up right below 70% correct as well. Breaking the 70% barrier over the season seems to be rather hard to do as seen on the Prediction Tracker . Looking into the statistics of those games reveals some interesting information. In the majority of those games, the losing team had better box scores but still lost the game. We had thought that incorporating the betting line data this year would have had impact but the accuracy of the straight up predictions is not significantly better than last year. The season isn't over yet and anything can happen so here are the predictions for week 15. Favorite Spread Underdog Discrete Pagerank DAL 7 at TB DAL DAL at NYG 10 WAS NYG NYG ...

Week 14 of the 2011 NFL season is upon us. Talk of play-off teams and Superbowl probabilities fill the airwaves even more than Christmas music. Sitting in traffic on the drive home from work tonight I was listening to a few on-air personalities discussing Green Bay and New England for the Superbowl. Green Bay has already clinched a playoff berth and many people would say they are headed to the Superbowl this year. The comment that caught my attention was that the defense for both teams was terrible this year and the only reason they were doing well this year is that their offenses were so good that they could "outscore their mistakes". This led me to think about the Colts without Peyton Manning this year. For the past 3 or 4 years the Colts with Manning as their quarterback have dominated the sport. It would seem that they built the entire team around Manning. The Colts would run up the score on offense and then the opposing team would be forced to attempt to pass often jus...

I am back from San Diego and while I ran into some computer problems while I was there, thankfully the results of my trip were much better than the results of last weeks predictions. Our discrete winner predictor is based on a Sequential Minimization Optimization (SMO) method for training the Support Vector Model (SVM). In our experiments, the SVM has proven to be one of the best binary classifiers for predicting the winner/loser of NFL games. As I mentioned a few weeks ago, this year we have incorporated the betting line data into the classification model as a form of collective intelligence. The betting line data quickly began to dominate the output of the prediction model followed by passing efficiency and turnovers in importance to the outcome. The result of favoring the betting line is that the classifier usually follows the favorite and when there are a number of upsets like last week, then our results are below expectations. Indeed many of the experts did not fare that w...

Our neural network predictor was 68% correct straight up this past week but overall our results were not awe inspiring. Two of the games that almost everyone got wrong were the Eagles-Bills and Seahawks-Giants games. In both games the favorite lost and one of the crucial stats was interceptions. Michael Vick of the Eagles threw four interceptions and Eli Manning threw three for the Giants. This is completely out of character for either of the quarterbacks. So far this year our Support Vector Machine (SVM) predictor has tracked the favorites very closely. With the addition of the line data this year, the line value has driven the output of the SVM. Ignoring the Line values, passing efficiency and turnovers forced by the defense have been two of the most dominant statistics. Predictions for week 6: Favorite Spread Underdog Discrete Pagerank At GB 14.5 STL GB GB At PIT 9.5 JAX PIT PIT PHI ...

Week 4 performance was rather pleasing. Straight up and against the spread were 80% and 75% correct. Buffalo lost with that last minute field goal and as to why Philadelphia fell apart in the second half and lost a 20 point lead has been the subject of numerous commentator's discussions. Hopefully the predictions continue to perform at this level but pessimism indicates that they will regress to the mean.  Week 5 of the NFL season means the commencement of bye weeks. This week's teams on bye are the Baltimore Ravens, Cleveland Browns, Dallas Cowboys, Miami Dolphins, St. Louis Rams and Washington Redskins. For comparison purposes we have included one of the better performing algorithms from the past two years. The PageRank algorithm that we modified to indicate strong teams averaged 68% for straight up predictions over the past two years. A more detailed explanation is provided in one of our previous posts . The predictions for Week 5: Favorite Line Unde...