Dusty Baker would like a do-over.

He’s still pained by what happened his first year as a big league manager. His San Francisco Giants finished with a whopping 103 wins — yet missed the playoffs.

“I went to the ballpark every day for 10 days to watch on TV,” he recalled this spring. “Finally, my wife told me I had to let it go. I was hurting.”

No such worries in baseball 2012.

Heck, Albert Pujols and his new teammates with the Los Angeles Angels could finish in third place — in a four-team division, mind you — and sweep the World Series.

The major leagues are now a major free-for-all, starting this Wednesday when Seattle and Oakland open in Tokyo. Credit (or blame) goes to an expanded postseason format that adds two more wild-card clubs this October.

So good luck in your farewell season, Chipper Jones. Welcome back, Andy Pettitte and Manny Ramirez and nearly 50-year-old Jamie Moyer.

Glad you’re feeling better, Buster Posey and Johan Santana and Adam Wainwright. Get well soon, Ryan Howard and Miguel Cabrera and Chris Carpenter.

Hope to see you around, Johnny Damon and Vladimir Guerrero and Roy Oswalt. And nice you could make it, Jesus Montero and Matt Moore and, in due time, fellow rookie Bryce Harper.

Because it seems like almost everyone is in the playoff race this season.

In Boston, fans want the 100th anniversary of Fenway Park to become a yearlong celebration of Valentine’s Day. In Texas, the two-time American League champion Rangers are a worldwide attraction with Yu Darvish.

In Miami, it’s all new: the ballpark, the lineup, the uniforms, the expectations — and Ozzie Guillen. Mark Buehrle, who pitched for the excitable manager with the Chicago White Sox, provided a preview for Marlins newcomers Jose Reyes, Carlos Zambrano and Heath Bell.

“Ozzie keeps everybody loose,” Buehrle said. “When he’s talking to you, you kind of laugh and giggle. And when he turns around and walks away, you look at everybody and say, ‘Does anybody understand what he said?’ ”

There’s hope, too, in Washington and at Wrigley Field, where the Cubbies’ faithful want to believe Theo Epstein will end a championship drought dating to 1908.

It’s possible. Know this: Five of the past 15 World Series champs have been wild cards, including the St. Louis Cardinals last season.

To Detroit manager Jim Leyland, whose team won the AL Central by 15 games and then signed Prince Fielder, an expanded postseason field is OK.

“There are a lot of mixed emotions, but as long as the playoffs don’t get watered down, it’s fine, but that won’t happen in baseball,” he said.

To World Series MVP David Freese, it’s all right — up to a point, anyway. Remember, his Cardinals were 10 1⁄2 games out of first place in early September and made the playoffs under the previous system.

Of course, the Cardinals benefited from a monumental collapse in the final weeks by the Braves. Tampa Bay, meanwhile, took advantage of a similar meltdown by the Red Sox.

The result was the most thrilling day in recent baseball history, when the playoff picture changed by the pitch during the last hours of the regular season. In the aftermath, Bobby Valentine was hired to replace Terry Francona as Boston’s manager.

Baseball hopes the extra wild cards will mean extra excitement all year long.

“I see where it’ll bring more interest to more cities, and that’s good,” Freese said. “But I’m old school. You go through a six-month grind for a reason. I’m fine with 10 of 30 teams making the playoffs, but I wouldn’t want to see any more.”

Traditionalists, take heart. The total number of playoff qualifiers remains fewer than the other pro sports — 12 of 32 are rewarded in the National Football League, and 16 of 30 advance in both the National Basketball Association and the National Hockey League.

And, it’s pretty certain to stay this way in baseball for a while. Players’ union head Michael Weiner recently assured that adding two playoff clubs was not the first step toward approving several more.

As it stands, the two wild cards in each league will hold a one-game playoff to see which team reaches the next best-of-five round.

Cleveland Indians president Mark Shapiro has changed his thinking on the subject.

“Originally, I was against adding a one-game playoff, but count me as a reluctant convert. I did not think a 162-game season should come down to one game for a team,” he said. “After listening to what Joe Torre, Tony La Russa and Jim Leyland had to say about it in discussions this winter, they convinced me.

“This is a good thing from a baseball standpoint. It places a greater significance on winning the division. I have always been an advocate of that,” Shapiro said. “It also energizes more fan bases simply because more teams should have a chance to get into the postseason.”

To Shapiro, perhaps the most memorable win in the Indians’ history came in a one-game playoff against Boston for the 1948 AL pennant. He also pointed toward the Yankees-Red Sox playoff in 1978 — the Bucky Dent game — and more recent matchups of Padres-Rockies, Tigers-Twins and White Sox-Twins.

“You look at all of the one-game playoff scenarios in baseball history and they have been classics. Those are among the best, most memorable games from an historical standpoint,” he said.

Baker would like to get a piece of that action. His Cincinnati Reds made the playoffs in 2010, but they missed in 2011.

He predicts the expanded playoffs will affect every club throughout the season.

“It is going to cut down the number of teams who are sellers at the trading deadline for one thing,” Baker said. “More teams are going to think they have a chance. And buyers probably are going to be more eager to get that player they think can win it for them.

“Look at St. Louis last year. They were patient, they were buyers, and they got into the playoffs and won the whole thing,” he said. “Wild cards have fared pretty well, but I think the new format is going to have an impact on the wild cards.”

Not always in a good way, either.

“Now,” Baker observed, “that wild card may have to use its No. 1 starter in the one-game playoff to get in. Where does that leave them in the next series? Or do they have a deeper rotation and can afford to hold back their No. 1 and then use him the next round?”

Baker lamented that he never got that chance in 1993. Shifting a toothpick from the right side of his mouth to the left, he winced at the memory of his 103-win Giants team that went home.

San Francisco lost the National League West to Atlanta on the last day. Back then, only the division champion made the playoffs. Wrecked, the Giants headed home. Well, most of them. Baker kept driving to Candlestick Park.

“It was heartbreaking,” he said. “Heartbreaking for me and for my team. It was one of the best teams I ever had and all we could do was watch the playoffs on television.”

Other things on deck this year:

• Five new managers, including Valentine and Guillen. Mike Matheny takes over for La Russa in St. Louis, Robin Ventura replaces Guillen with the White Sox, and Dale Sveum is running the Cubs instead of the fired Mike Quade.

• This could be the final season for Yankees closer Mariano Rivera. Old pros Derek Jeter and Jim Thome are back, while Jorge Posada and Jason Varitek have retired.

• Pittsburgh will try to end its slump of 19 straight losing seasons. Baltimore, marking its 20th anniversary of Camden Yards, has had 14 losing years in a row.

• The All-Star Game will be in Kansas City and, as part of baseball’s new labor deal, there will be a four-day break. There will not, however, be expanded replay to cover fair-or-foul calls, trapped balls and fan interference all over the park.

• The sale of the Los Angeles Dodgers is due to be closed by the end of April, with owner Frank McCourt picking the winner of the bankruptcy auction from among groups cleared by Major League Baseball. Also, a settlement between the New York Mets’ owners and the trustee for Bernard Madoff’s fraud victims might let the team put its focus back on the field.

• The Hall of Fame ballot that will be mailed out around Thanksgiving will be among the most intriguing one in a long, long time. How will voters treat first-time candidates Barry Bonds, Roger Clemens and Sammy Sosa in light of the steroid cloud?