When looking for X-factors in Super Bowl XLIV, we can start with two safeties -- Antoine Bethea(notes) of the Colts and Darren Sharper(notes) of the Saints. Both men are key players in the defenses that helped their teams get this far, and both men are facing brilliant quarterbacks who will want to put them on strings in different ways.
For Bethea, the challenge will originate from the Saints' surprisingly high-quality running game, and the play action it allows. According to Football Outsiders, the Colts allowed 7.5 yards per pass play this season on play action fakes, and 5.6 on all other pass plays. This is one downside to having a defense that is, above all, fast at first bite -- the Colts run to the ball in a big hurry and ask questions later. And while their linebackers are trained to do this, Bethea will have to show a bit more restraint to avoid having one of New Orleans' many talented receivers blowing right by him in a deep route as he's recovering from one of Drew Brees'(notes) play action specials.
The Saints ran more play action than any other team in the NFL this year, and they averaged 7.6 yards per play when they did it. Correspondingly, the Saints were the best team in the league on yards per play on deep passes (passes of 15 yards or more) -- these plays averaged 17.0 yards per play, and Saints receivers caught those deep balls 55 percent of the time (the averages were 11.8 yards per play and a 40 percent catch rate). If Brees can draw Bethea in, the Colts are in big trouble. And if Bethea simply hangs back and waits for the big play -- well, that's one less defender the Saints have to worry about when they run the ball.
On the other side of the ball, Sharper leads a defense fortified by turnovers above all. He is one of the best in the NFL at reading a quarterback's intentions, and though he doesn't have the closing speed he used to, he makes up for any athletic diminishments with a football intellect that allows him to take the correct angle more often than most. Sharper will play fairly deep most of the time, and I wouldn't expect to see him at the line too often. New Orleans defensive coordinator Gregg Williams may have Sharper doing some things closer to the line as the linebackers drop into coverage.
The real challenge for Sharper is that the Saints haven't been great against multi-receiver packages -- according to FO's defensive metrics, they're most vulnerable against second and third receivers. That's a major problem against a Colts team where the best receiver is always the open one, and newbie receivers Austin Collie and Pierre Garcon have been ripping it up in the playoffs. The pressure will be on Sharper to not just capitalize on potential turnovers, but to keep that Colts offense under wraps to whatever extent it can be done.