New generation of QBs emerge but league faces threats MIAMI (Reuters) - A new generation of talented quarterbacks emerged in 2012 but a refereeing fiasco, worries over concussions and player behavior all left their mark on the National Football League (NFL). The year was also a tantalizing tale of the Mannings with New York Giants quarterback Eli Manning winning his second Super Bowl title in four years with a win over New England in the same stadium where older brother Peyton played for Indianapolis. After a year out with serious neck problems, Peyton Manning restarted his career with the Denver Broncos after 14 years with the Colts and quickly cast aside any doubts over his durability by leading his team to a playoff berth and division title. Manning's revival came at the expense of Tim Tebow, the most talked about player in 2011, who has spent most of this year on the sidelines after being traded to the New York Jets. 'Tebow-mania' reached its peak in January when he led the Broncos to a playoff win over Pittsburgh but a crushing loss to the New England Patriots a week later was the last in a Denver uniform for the unorthodox quarterback. Tebow's charisma, his noted religiosity and clean-cut good looks made him one of the most popular NFL players in years but that did not stop Jets head coach Rex Ryan leaving him as a bit-player and back-up to Mark Sanchez with most critics agreeing that Tebow's poor passing technique has hampered his career. Tebow's fans understandably view 2012 as a year in which an exciting player's talent was wasted but in the big picture there has been no shortage of exciting new talent to enjoy in the NFL. It was hard to imagine anyone exceeding the record-breaking impact made in 2011 by Carolina Panthers rookie quarterback Cam Newton but it did not take long for the top two picks in this year's NFL Draft, Indianapolis's Andrew Luck and Washington's Robert Griffin III respectively, to make an impact. Luck ushered in the post-Manning era faster than anyone had imagined, with his outstanding passing and classy composure indicating he is a player who could enjoy similar dominance to his predecessor. Griffin, or RG3 as he is widely known, is a different quarterback altogether - his speed and courage make him a genuine double-threat, able to rush but he is also, as critics of Tebow have noted, an accomplished pocket passer too. Seattle's Russell Wilson and Miami's Ryan Tannehill have also made good impressions in their rookie years and with Tom Brady, Drew Brees, Aaron Rodgers, Ben Roethlisberger and the Mannings still on top of their game, it has become an era of unprecedented passing yards for quarterbacks. Given the key role quarterbacks play, the abundance of talent at the position should mark a golden-era for America's most popular league but the game has a nasty underbelly which has been revealed on several occasions this year. The NFL has long been plagued by off-field problems, most notably domestic violence, gun crime and drunk driving, and there have been tragic examples of all three this year. Kansas City Chiefs linebacker Jovan Belcher fatally shot his girlfriend at their home moments before killing himself in front of his coach and general manager at the team's training facility in December. A week later, Dallas Cowboys defensive tackle Josh Brent was charged with intoxication manslaughter after the car he was driving flipped over and caught fire, killing team mate Jerry Brown, a passenger in the car. In May, former San Diego Chargers linebacker Junior Seau, a 12-time Pro Bowl selection, was found dead at his home in May, with a self-inflicted gunshot wound to the chest. The manner of Seau's death and his families willingness to let his brain be examined for evidence of the impact of repeated injuries from his playing days, brought the issue of concussions back into focus. Over 1,500 former football players have sued the NFL over head injuries and there have been accusations that the league concealed links between the game and brain injuries. The NFL has disputed those allegations and points to its intensive education work on the issue and also the stricter new regulations covering treatment of players who are concussed. Concern over the potential impact of excessive violence on players was also behind NFL Commissioner Roger Goodell's strong sanctions against the New Orleans Saints, a story that hung over the league for much of the year. The Saints were accused of running a bounty program from 2009-2011 that gave players cash rewards for knocking opponents out of games. While Saints head coach Sean Payton was suspended for the entire season and other members of the coaching staff received shorter bans, much of the attention was on the sanctions given to four players, all of whom had their punishments overturned. The decision by former NFL Commissioner Paul Tagliabue, with little compelling reasoning behind it, was a strange end to an affair which did little good for the league's image. That image also took a hit from the contract dispute with referees which led to an early season lockout and resulted in some farcical decisions By the replacement referees. The dispute culminated in botched call in a nationally televised game that handed Seattle victory over Green Bay and caused so much outrage that a deal was swiftly reached for the regular refs to return in early in the season. But while referee dispute, off-field troubles, bounty schemes and concussion fears generated plenty of negative attention for the league they did nothing to weaken the NFL's position as the dominant sport in North America and the top draw on U.S. television. Reporting By Simon Evans; Editing by Frank Pingue