Maybe it was the 8:30 p.m. starting time.
Or the fact that the game was played on Saturday night, a party night.
Maybe it was the January-type frigid temperatures.
Or maybe it was just a crowd of disgruntled fans unhappy with the Buffalo Bills' tough season.
Whatever the reasons, Saturday night's loss to the Denver Broncos was witnessed by one of the worst-behaved crowds at Ralph Wilson Stadium in recent memory, authorities said Monday.
The main culprit was obvious: alcohol.
"I don't like night games in winter in Buffalo," Orchard Park Police Chief Samuel M. McCune said. "I don't like night games at all, especially on a Saturday. It gives people more time to get lubricated."
Fans who like their alcohol had all day to drink -- and all Sunday to recuperate.
Things got so bad Saturday night the Bills decided to cut off beer sales after the first quarter, something they hadn't done in at least 10 years. Beer normally is sold through halftime.
"In monitoring the situation, we realized that there seemed to be more intoxicated fans [than usual] around the concession areas," said Scott Berchtold, the team's vice president for communications. "So we made a decision to cut off the beer sales."
Authorities on Monday detailed what a tough night it was for fans and for those who keep the peace:
* A late-arriving crowd created what several fans called a chaotic scene at many ticket gates.
Patrick M. Howard, security manager for Apex Security at the stadium, remembered seeing the stadium virtually empty just before kickoff, while the parking lots remained filled with bonfires. The last-minute rush to the gates left many fans waiting 20 to 25 minutes, or more, to get inside.
"At some of the gates, people were still trying to get in at 9 o'clock," Howard said.
* Authorities logged 22 arrests, compared with the usual average of about 10 arrests. Sixteen of those arrests were inside the stadium, six outside.
* Security officers had to break up more fights than normal.
"We had a lot more assaults than usual, four or five at least, and there were a lot of fights in the stands," McCune said.
Pat Braun, a 21-year-old Bills fan from Amherst, said he noticed quite a few fights, both in the crowd waiting to get into the stadium and in the stands.
"It was surprising to see how many Bills fans were going after each other," he said. "The fans were really, really frustrated with each other and with the team."
* To put an exclamation mark on the rough night, one bold -- or totally wasted -- fan had to be corraled by security officers when he dashed onto the field near the end of the game.
He wasn't streaking. He wasn't wearing a jacket or shirt, but he had his pants on, to ward off the 29-degree cold.
Howard also noted several other signs of the excessive drinking, including a lot of fans either falling or vomiting.
"We had a busy night, and a lot of it was alcohol-related, from start to finish," Howard said. "There wasn't a whole lot of fan consideration, from one fan to the next."
Howard then added a postscript felt by other law enforcement officials: "Night games are tough."
The rowdiness at Saturday's game may kick-start the debate over night games at Ralph Wilson Stadium.
For years, in the mid-1990s, Bills officials preferred not to have any regular-season night games, because of the large numbers of fans having to drive back to the Rochester and Syracuse areas so late at night.
The Bills hadn't played a regular-season home night game for five years, since the season opener against Tennessee in 2000. They had played only two prime-time home games in the past 10 years.
But the Bills' position has changed in recent years, partly because of the desire to showcase the team in front of a national television audience.
"We're grateful for any prime-time game we can get," Berchtold said. "There's an air of excitement for the fans."