The Tigers' shortstop had his worst year at the plate since 2003, when he was a 21-year-old rookie. This year's .239 batting average, .305 on-base percentage and 63 RBIs were all his lowest marks since his rookie year. They were also the lowest of his career as a starter.
For Peralta, it was especially disappointing given he hit a career-high .299 in 2011 while making his first All-Star team. However, something clicked for the shortstop once the postseason began. He can't really explain it, and neither can manager Jim Leyland, but Peralta has suddenly found that 2011 form.
"My offense in the regular season, I don't do how I'm doing right now. It's better for me at this moment than in the regular season," said Peralta, who is batting .343 in the playoffs and hit .388 in the American League Championship Series.
In nine postseason contests, Peralta has five multihit games. Comparatively, he had one in September. You would have to count backward from the final day of the regular season to Aug. 15 -- 43 games -- to add up five games with multiple hits.
"That's what I wanted to show. I wanted to show that I can do it," he said. "The postseason is different baseball, the best moment, that you need to show it here. And it's happening right now."
There's perhaps no at-bat that shows how impressive Peralta has been during the Tigers' World Series run than his fourth-inning battle against Yankees ace CC Sabathia in Game 4.
Peralta's never hit Sabathia. He's 2-for-23 against the lefty in his career. His track record had been so poor that Leyland kept Peralta out against Sabathia in three previous matchups this year.
But with how the shortstop has hit in the playoffs, the skipper let him play. And the reward was a two-run blast over the left-field wall, making the score 6-0 and all but sealing Detroit's first trip to the Fall Classic since 2006.
And if that shot didn't seal it, it was Peralta's second homer of the night in the eighth.
"He's played great. He's made some huge plays on the field and huge plays with his bat," catcher Alex Avila said. "Just as big as Delmon [Young's] been."
Young was named ALCS Most Valuable Player, but Peralta was awfully close to stealing the award.
For Peralta, it's not just a revitalized bat, either.
He's been criticized this season for his defense. He makes the routine play, but he's slow at getting to grounders in the hole, which is especially costly given that Miguel Cabrera isn't the most agile third baseman.
However, he's appeared quick and others have taken notice.
"I really don't [know how to explain it]. I don't," Leyland said. "Things happen, and I wish I could put my finger on it, but I think Peralta, for whatever reason, is moving better. He seems lighter on his feet than he has been all year."
The defense in general has played much better. Pitching is the key reason Detroit is where it is, but the defense deserves honorable mention. And especially Peralta.
Peralta made a few highlight-reel plays in Games 1 and 2 of the ALCS at Yankee Stadium. His most notable were in Game 2, when he made two crucial run-saving stops to prevent New York from taking a lead.
First it was a grounder by Mark Teixeira. Peralta dove and made a backhanded grab to stop Ichiro Suzuki from scoring from second. Then it was a barehanded stab at a slow-roller to peg Russell Martin at first and end the inning with a runner on third.
Although Leyland couldn't explain it, Peralta could.
"I just try to learn more about the position. I know how to play every hitter, and that's what made me better in the field," he said. "I've been moving better and I've been working out with the training guys. It's helped a lot."
As difficult as it is to explain Peralta's sudden improvement, it's equally tough to explain the season-long slump at the plate. But Tigers president/general manager Dave Dombrowski had one sensible theory.
"People forget that he had a lot of things going on in his life. He had twins. He had to leave them behind, his wife behind," Dombrowski said. "I saw his wife here the other day for the first time, really, all season long because of the circumstances."
Regardless of the reason, what matters to the Tigers is that he continues providing what they had come to expect after last year. And if he does, it could mean a World Series ring.
"He's making his plays, so I think having him in the field and in the lineup every day has helped make a big impact," reliever Joaquin Benoit said. "We've got a lot of guys up and down this year, hitting-wise, but now that he's getting back to what he was last year, I think he's going to be a big help for us if we win [the World Series]."
Anthony Odoardi is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.