Five keys to who wins Super Bowl XLVII

The early betting money on Super Bowl XLVII heavily favored the underdog Baltimore Ravens, which is why the San Francisco 49ers dropped from 5-point favorites to 3 ½-point favorites.

The point-spread won't matter to either team Sunday evening, and contrary to whatever Ray Lewis might say, God won't decide the outcome of this game, either.

But there are some legitimate keys to the outcome, and here are five to consider:

Won if by landNiners quarterback Colin Kaepernick has a major-league fastball and shocking accuracy. Ravens quarterback Joe Flacco throws arguably the best deep ball in the NFL.But neither team will win without getting it done on the ground.San Francisco's offensive line is widely considered the top run-blocking unit in the NFL, and the 49ers averaged 37 more rushing yards (155.7) per game in the regular season than the Ravens. In the postseason, the Niners have been even better, rushing for 472 yards in two games. Kaepernick ran for a record-setting 181 vs. the Green Bay Packers, and the late-season emergence of rookie LaMichael James gives San Francisco two dangerous options behind bell cow Frank Gore.For five years, the Ravens have run with Rutgers' Ray Rice, but they also got a boost from a rookie this season. Bernard Pierce rushed for 532 yards in the regular season and is averaging 6.3 yards per carry in the postseason.Run defense? The 49ers were No. 4 and the Ravens No. 20 in yards. But in average gain allowed per rush, they were much closer. The 49ers were tied for third, while the Ravens were tied for seventh.Home sweet homeSuper Bowl XLVII will be played at the Louisiana Superdome, so, just like every other Super Bowl, there is no home-field advantage. However, the 49ers have a lot more experience this season playing indoors than the Ravens. The Niners played four games inside this season, including one at the Superdome. But they only split those four games, losing at Minnesota and St. Louis and winning at New Orleans and in the NFC title game at Atlanta. The NFC champs also played on a Monday night at the Cardinals' University of Phoenix Stadium, but the retractable roof was open during the 49ers' victory. The Ravens played only one game this season in a dome, and they gave one of their worst performances of the season in a 34-13 loss to the Texans at Reliant Stadium.Something specialFor the 49ers, it has been the best and worst of times on special teams. Andy Lee has a monster leg. He was one of just two NFL punters who had more than half his kicks downed inside the opponent's 20-yard line this season. He also has two of the three best single-season net averages in NFL history, including the all-time best of 44.0 in 2011.But 49ers place-kicker David Akers missed 13 of 42 FG attempts in the regular season, more misses than anyone in the league, and he clanked another miss off the upright in the NFC title game.If this game comes down to a late field goal, the Ravens have to love their chances, even though their kicker is a rookie. Justin Tucker converted 30 of 33 FG attempts, including three game-winners, the most recent of which came in overtime of the divisional-round playoff game at Denver.Here's to your healthThere aren't a lot of serious injuries, but outside linebacker Aldon Smith (shoulder) and defensive end Justin Smith (torn triceps), arguably the 49ers' two most valuable defenders, are both less than 100 percent. Justin Smith, who demands frequent double-teams when healthy, was injured late in the Dec. 16 victory over the Patriots. Aldon Smith, who has been limited this week in practice, hasn't had a sack since then, although he had 19 frac12; before that. Niners linebacker Ahmad Brooks (shoulder) has also been limited. For the Ravens, tight end Dennis Pitta (thigh) and linebacker Dannell Ellerbe are nursing injuries, but both have practiced. Pitta was the Ravens' second-leading pass catcher in the regular season and in the postseason. Combined, he has 9 TD catches.All five are expected to play, but playing and playing at 100 percent are different, and that could mean the difference between winning and losing.Been there, done thatThe 49ers were 4 points short of playing in Super Bowl XLVI a year ago, but before that they won just 26 games in four years. The Ravens have been to the postseason for five straight seasons, every year that quarterback Joe Flacco has been in the NFL. Five Ravens starters on defense have also been around for all five playoff seasons. Nine players on the roster have spent at least 10 seasons in the NFL, and seven are starters. Their roster would be considered old if the Ravens weren't a perennial playoff team. Since they are, they're considered experienced.The 49ers are much younger, with seven starters who have three years' experience or less. If they win, they're precocious; if not they're inexperienced.