JERSEY CITY, N.J. -- He is the X factor, the unknown addition who everyone knows.

Seattle Seahawks receiver Percy Harvin will play in Super Bowl XLVIII. If this was your company softball team playing for the league title, you’d be adding a ringer moments before the first pitch.

It is one of the most unusual situations ever, adding a Pro Bowl-caliber player who only played in six quarters all season, for the biggest event in sports.

Seattle is excited to have Percy Harvin healthy and in the lineup for the Super Bowl. AP Photo/John Froschauer

In the view of some fans, Harvin was supposed to be the final piece to get the Seahawks to the Super Bowl. They accomplished that without him, but can he help them win it now that he’s back?

“It’s not about me,” Harvin said. “I’m just adding another playmaker. We already have three or four good receivers out there. I’m just adding to the mix.”

The mix now has a player who might be the fastest man in the NFL. Speed is a dangerous thing when you add in all the other skills Harvin possesses -- a precise route-runner, elusive ball carrier and explosive kick returner.

“His acceleration is unbelievable,” Seattle tight end Zach Miller said. “He’s a playmaker. Once he gets the ball in his hands, he is so explosive and so fast. He’s definitely a threat to score every time he touches the ball.”

Harvin has started almost every interview this week with this statement: “I’m just glad to be here.”

Obviously, but considering what he has endured this season, it’s a little like leaving a prison cell for a penthouse suite on Park Avenue.

He signed a six-year, $67 million deal with the Seahawks last March and was widely viewed as the offensive weapon that would propel the Seahawks to the next level. But Harvin had major hip surgery on Aug. 1 to repair a torn labrum.

He returned Nov. 17 for the game against his former Minnesota Vikings teammates, showing his talent with a 58-yard kickoff return and a spectacular one-handed catch on a third-down play that kept a scoring drive alive.

Maybe it was too much too soon. Harvin aggravated his hip injury, which became inflamed afterward. He missed the rest of the regular season. Seattle coach Pete Carroll was about to put Harvin on injured reserve before the playoffs started, but Harvin convinced Carroll he could play.

Harvin caught three passes in the New Orleans playoff game, but suffered a concussion at the end of the first half. He didn't make it through the mandatory concussion protocol in time to play in the NFC Championship Game against San Francisco.

“It’s been weird, frustrating, disappointing, all the above, man,” Harvin said. “I had a tough time, and it wore on me a little bit. But my teammates have been A-plus-plus. This whole organization has been top of the line.”

Harvin said one teammate helped him more than any other.

“A couple times I was really down," Harvin said. “But [cornerback] Richard Sherman, I don’t know how he even read me, but he came up and said, ‘Man, I kind of see you’re really down. You’ll get through this. We have your back.’ I’m so grateful for that.”

Now Harvin is back for the biggest game of his life. And he’s smiling, something he hasn't done much of this season. He was grinning from ear-to-ear at every media session. Something has changed beyond the obvious. Harvin is healthy, finally, and he knows he has a chance to show what he can do on the NFL's biggest stage.

“You can really see it in his eyes,” Seattle offensive tackle Russell Okung said. “You know that anytime Percy gets the ball, he’s looking to run by a guy and score. Anytime you have a guy like that, he’s hard to beat. He has a zeal for the game. I can’t wait to have him out there. It’s almost something magical.”