MINNEAPOLIS -- If you spend some time around Adrian Peterson, you learn to decipher his mood from small distinctions on his eternally optimistic face. Peterson has a genuine smile, the kind he displayed as a rookie in 2007 when he set the NFL's single-game rushing record.

There is a sardonic smirk that approaches a scowl. I've seen it at least once -- when his erratic performance in the 2009 NFC Championship Game contributed to a loss against the New Orleans Saints.

And then there is the conflicted grin, the kind we saw plastered on his face Sunday evening after he finished just short of breaking Eric Dickerson's single-season rushing record. His 199-yard performance was critical to the Vikings' 37-34 victory over the Green Bay Packers, one that clinched the NFC's final wild-card spot. But it also left him eight yards shy of Dickerson's 2,105-yard mark, and Peterson was nothing if not honest when he said afterwards that he had "a bittersweet feeling inside."

Peterson seemed genuinely thrilled to be part of a playoff team for the third time in his career. But ever since tearing two knee ligaments exactly 371 days ago, Peterson had envisioned his season ending with team and individual accolades. When reporters entered the Vikings' locker room some 20 minutes after the game, Peterson was still in full uniform, accepting well-wishes and hugs from teammates and Vikings staffers who all knew how close they came to history. Then Peterson spent a good portion of his interview session toggling between disappointment and pride.

"The first thing that came to my mind when I heard that was nine yards short was, 'It is what it is. It wasn't meant to happen,'" he said. "Not to say it doesn't hurt, because it does. But ultimately we came in here and accomplished the ultimate goal of getting a win and taking our team to the playoffs."

How close did Peterson come? His final run of the regular season was a 26-yard scamper that set up Blair Walsh's game-winning 29-yard field goal. Had he scored a touchdown on that run -- by perhaps breaking one more tackle and running another 11 yards -- he would have finished the season with a new record of 2,108 yards.

"I'm not going to think about it that much," he said. "I'll still think about it a little bit, but ultimately it is what it is."

Now comes a question we can't answer for another six weeks: Will 2,097 yards and a playoff berth be enough to make Peterson the NFL's MVP? We've spent a good portion of this season debating the value of running backs versus quarterbacks, and it's worth noting that for all of Peterson's yardage, the Vikings wouldn't have won Sunday were it not for a number of clutch throws from quarterback Christian Ponder. Those who favor quarterbacks for this award will no doubt lean toward the Denver Broncos' Peyton Manning.

Peterson didn't leave any doubt about his position, however.

"I can't say I don't want to [win it]," he said, "just like I wanted to break the record. Either way, in my heart, I'm the MVP, and that's all that matters."

He didn't break the record. He might not win MVP. But Peterson could say one thing for sure Sunday night: He is a playoff participant. And that's worth smiling about. Right?