The regular season has ended, with a spectacular final night of unfolding drama for multiple teams with playoff aspirations, ending with ecstasy for the Rays and Cardinals, and agony for the Braves and Red Sox.

The postseason has ended, with a World Series that was the most exciting any of us have seen in years — including a Game 6 many are calling the best ever.

Now comes the offseason, which is the precise opposite of the leisurely respite its name implies. Rather, it is the primary opportunity for teams to tweak — or remake — their rosters in pursuit of participating in next year's postseason.

For the Mariners, this is an offseason of especially keen importance, as they try to regain their relevance and appease their increasingly frustrated fan base.

I realize that sentiment could (and probably has) been uttered at the outset of every Hot Stove period. But this year, despite the promise shown by a variety of young players, the Mariners have an obvious need to augment their lineup with some proven bats. General manager Jack Zduriencik can be expected to be aggressive both in free agency and on the trade front.

Depending on where the payroll is set — a huge question as yet unanswered — they could have some money for Zduriencik to play with. The contractual obligations to Milton Bradley/Carlos Silva, Adam Kennedy, Jack Cust, Yuniesky Betancourt (who was still getting $1 million via the M's last year), and likely David Aardsma (a strong candidate to not be tendered a contract) will be gone, saving some $28 million.

Some of that will be eaten up by raises to Felix Hernandez (whose salary goes up by $8.5 million to $18.5 million), Franklin Gutierrez and others. But there still could be an opportunity for Zduriencik to add some significant players.

Beginning Sunday, clubs have four days to negotiate exclusively with their own free agents (which for the Mariners are Josh Bard, Adam Kennedy, Wily Mo Pena and Jamey Wright). On Thursday, major-league and minor-league free agents may negotiate and sign with clubs other than their own.

The big-ticket items this year are Prince Fielder and Albert Pujols, with the former a natural target for the Mariners if they decide to aim big. The next-biggest names are Jose Reyes and Carlos Beltran, both of whom would fit just fine in Seattle, yet it's hard to envision either one ending up with the M's.

Other names on the list that could draw their interest are David Ortiz (who began his career in the Mariners organization), Josh Willingham, Michael Cuddyer, Jason Kubel and Aramis Ramirez. It's not a great crop of free agents, to be frank, though the list could grow via three methods.

• First, many players have team options that must be picked up or declined by three days after the World Series. Those that are declined become free agents; Brad Lidge, Roy Oswalt, Joe Nathan and Ryan Doumit have already been set free by their teams in the past week, and the likes of Grady Sizemore, Fausto Carmona, Octavio Dotel, Yuniesky Betancourt, Aaron Hill, Ryan Dempster and Marco Scutaro could be in the next week. Others, like Robinson Cano, James Shields, Yadier Molina and Brandon Phillips, are no-brainers to have their options picked up.

Sizemore, who is from Everett, and Doumit, from Moses Lake, are possible Mariners targets. Sizemore, who played his formative years for Eric Wedge in Cleveland, is particularly intriguing, because he was an impact bat until injuries sabotaged his career. He has had five operations in the last three years, the most recent a knee procedure after this past season. The risk is high, but so is the upside if, at age 29, Sizemore can again become the player who had a .907 OPS in 2006 and 30 homers and 30 steals in 2008.

• Another method of adding to the free-agent pool will come Dec. 12, when teams must decide whether to tender contracts to their arbitration-eligible players. The Mariners are likely to "non-tender" Aardsma, who underwent Tommy John surgery in July, but may well re-sign him, at a lesser price, to continue his rehab.

• Third, there could be some significant Japanese free agents this year, namely pitchers Yu Darvish and Hisashi Iwakuma. The former would have to be "posted," which is the method by which Ichiro joined the major leagues a decade ago. It's a two-pronged process by which an MLB team must put in the highest bid merely to win negotiating rights, and then it has to reach contract agreement with the player.

Darvish said he hasn't yet decided if he'll go that route, despite recent stories out of Japan that he will be posted in early November. Iwakuma, one of the top starters in Japan, would be an unrestricted free agent if he chose to come over. He posted last year but failed to reach contract agreement with the A's, who won bidding rights, and returned to Japan for the 2011 season.

Darvish, considered the best pitcher to come out of Japan since Daisuke Matsuzaka — and rated ahead of Matsuzaka by many scouts — would seem redundant to a Mariners team that has Hernandez and Michael Pineda on staff and a spate of highly touted young arms on the way.

On the other hand, if the Mariners obtained Darvish, it could free them to use Pineda as the centerpiece of a blockbuster trade.

Among the bats that could be available this winter are David Wright, Kevin Youkilis and Carlos Quentin. If the Reds ever decided they had to trade Joey Votto for financial reasons — and they insist they won't do that — he would instantly jump to the top of the M's wish list (and many other teams').

It's going to be a fascinating few months of maneuvering, peaking with the winter meetings in Dallas. Let's hope the action is exciting as it was on the field down the stretch.

Note

• The Mariners are making a change in their front office, with Chris Gwynn replacing Pedro Grifol as director of minor-league operations. The official announcement was delayed because of the World Series, but should come early next week.

Gwynn, 47, is the brother of Hall of Famer Tony Gwynn and had a 10-year playing career of his own. Chris Gwynn has worked for the Padres for the past 12 years, the last two as director of player personnel.

Larry Stone: 206-464-3146 or lstone@seattletimes.com