INDIANAPOLIS—A secret strategist for the New York Giants won't be in Indianapolis for Sunday's Super Bowl bout against the New England Patriots. He won't even be in the U.S.

Neil Hornsby will be watching the game on television from his home about 30 miles from London. A north England native, Mr. Hornsby never played a down of football. Not until the age of 42 did he attend his first professional football game. Yet from watching games broadcast over the Internet, he has compiled research and analysis that the Giants and several other teams used this season to prepare for their opponents.

Neil Hornsby, at home in Luton, England, tracks NFL statistics from afar. Neil Hornsby

Now, from temporary offices in an Indianapolis Marriott, the Giants are using pieces of Mr. Hornsby's data as they get ready for the Patriots. "It's definitely valuable information," says Jon Berger, the Giants' director of football information, who for competitive reasons declines to elaborate.

Like those train spotters who stand along Britain's railways collecting locomotive data, Mr. Hornsby studies the National Football League in a way its most fanatical fans would find tedious. Using game footage available to anyone with Internet access, Mr. Hornsby and his team watch every player on every down that is broadcast on television, a process of such endless rewinding and replaying that each contest takes about 24 hours to analyze. "I get very little sleep," says Mr. Hornsby, 48 years old.

"I haven't started a support group yet," says his wife, Claire Hornsby, who dubs herself the United Kingdom's only "American football widow."

Mr. Hornsby grew up following his nation's most popular obsession, soccer. But while watching television in 1983, he underwent a road-to-Damascus-type conversion upon seeing some highlights of American football. Rushing out to buy a football magazine that happened to feature Dolphins quarterback Dan Marino on its cover, Mr. Hornsby became an instant Miami fan.

Inside the magazine, however, he discovered what he loves most: statistics. Yards per carry, completion percentage, sacks, fumbles, receptions—all this was candy to a man who held a physics degree and whose business consultancy provided process-and-program-management advice to the hotel industry.

The New England Patriots, Game by Game

New England rights the ship with a 37-16 road win at the Jets. Here star tight end Rob Gronkowski catches a second-quarter touchdown pass. Getty Images

Even so, for many years his only way of following live games was the Armed Forces Radio Network.

"It was so frustrating because the signal was always cutting out right at the crucial moments in the game," he says.

Then came the Internet, delivering game-footage galore. The more Mr. Hornsby watched and took notes, the more convinced he became that existing analysis of the game was neither complete nor entirely accurate. According to his research, hype often played a larger role than statistics in determining pay, playing time and Pro Bowl appearances. "Take everything you hear watching the game on television with a grain of salt," he says.

But in a sport teeming with armchair quarterbacks, who wanted to hear from Luton, England? Mr. Hornsby, after all, had only ever attended two professional games.

Then, in 2007, he launched his website, called Pro Football Focus. At first it made no splash. But gradually football junkies saw it offered unusual detail, including grades of how specific players performed in each game in each facet of the game. For instance, an offensive lineman would receive a separate grade for both pass blocking and run blocking.

Pro Football Focus was also keeping track of even more advanced data, that it hoped to sell to media outlets and, perhaps, football teams.

For a pass play, it didn't merely record who threw it, who caught it and how many yards were gained after completion. It kept track of how many seconds elapsed before the quarterback released the ball, where each player stood at the start of the play, which defensive player applied pressure and which blocker allowed it.

In 2009, the site came to the attention of the Giants' Mr. Berger, an executive of the team since the early 1980s. As director of information, Mr. Berger is the team's official wonk, entering every play by every NFL team into a database in search of trends and tendencies that might be useful for Giants coaches.

It was while "messing around on Google" that Mr. Berger came across Pro Football Focus, and one statistic in particular struck him: player participation. The site listed the number of times each player in the NFL participated in a play during a game. That is a statistic the NFL tracks and releases only to teams—never to the public.

Doubtful about the accuracy of Mr. Hornsby's data, Mr. Berger checked it against the NFL data set and found Pro Football Focus was nearly perfect. Impressed, Mr. Berger sent Mr. Hornsby a congratulatory note. Mr. Hornsby was so surprised he thought one of his friends had pulled a prank on him.

Today, the site provides customized data to five NFL teams, Mr. Hornsby says, as well as to sports agents seeking to bolster their players' arguments for fat paychecks. Mr. Hornsby won't say which teams or agents are paying for his data. But he says revenue is now great enough that he employs four analysts to help him study game footage, and 13 others to count how many downs each NFL athlete plays per game. He says he doesn't provide data to the Patriots.

Photos: The New York Giants, Game by Game


The Giants are a nonpaying user of the site. That relationship deepened last August when Mr. Hornsby requested a visit with Mr. Berger. The timing could hardly have been worse: With the preseason shortened by a labor dispute, August was busier than usual for Mr. Berger. But he agreed to meet with Mr. Hornsby, blocking out a full hour on his calendar.

The meeting lasted seven hours. Stunned at the material Mr. Hornsby produced from his laptop, Mr. Berger says he was especially intrigued by data showing where individual players most often line up on the field, and how they perform against certain formations and opponents.

"It was really impressive," says Mr. Berger, calling Mr. Hornsby the first outsider ever to supply usable data to the Giants.

What most amazes Mr. Berger is that Mr. Hornsby gathers his data using the television footage available to everyone. That footage is highly limited compared with the proprietary film—known as All 22—that the NFL gathers at each game and makes available only to team officials.

Mr. Berger says it is now customary for him to seek information from Mr. Hornsby about coming opponents. Mr. Berger says these communications typically begin with an email to Mr. Hornsby asking him to call Giants headquarters. That is because the teams' low-cost telephone system won't allow calls to England.

Write to Reed Albergotti at