The New York Mets' closer for roughly a month and a half last season, Bobby Parnell, certainly had his well-documented share of struggles trying to replace former closer Francisco Rodriguez who was traded to the Milwaukee Brewers in July.

The closer position will actually be one of GM Sandy Alderson's most important to fill this offseason, due to the lack of a strong in-organization candidate as of right now.

Parnell was the guy for the job but had performed so poorly as the closer towards the end of the season that it still isn't his job to have.

Alderson will most definitely have to look for an out-of-organization closer to fill the gap left by the K-Rod trade. It's good news for Alderson that this year's free-agent closer crop is much deeper than in year's past.

Lets take a look at some of the top candidates:

Joe Nathan, Minnesota Twins

The first guy that would be a nice fit for the Mets at closer would be Joe Nathan.

Nathan's team option was declined by Minnesota a few days ago after an ineffective 2011 season and a 2010 season lost to Tommy John surgery. Of course, this puts him on the open market and available to the Mets.

Nathan would be a nice sign for Alderson because he would come on the relative cheap and he also has ties to the New York Metropolitan Area. He graduated from high school in Ulster County, NY, which is only a few hours from Flushing in upstate New York.

He also went to Stony Brook University in Suffolk County, out on Long Island, for college ball. Nathan might be a little on the old side, but he would be perfect for a three-year deal with the Mets.

Francisco Cordero, Cincinnati Reds

After a very disappointing season for the Cincinnati Reds, in which they finished third in the NL Central after being predicted by some to win it, star closer Francisco Cordero finds himself without a contract.

This is definitely not because of his play, as he had a stellar season last year with 37 saves and a sub-2.50 ERA. He would be a huge acquisition for the Mets' front office as he provides a shut-down presence who, more often than not, will get the job done. The Mets need a guy like that to pitch the ninth inning.

The only issue with Cordero is that he may cost a little more than Sandy Alderson will be willing to pay for a closer especially considering the unstable financial state the Mets are faced with right now.

However, Cordero would definitely be worth the money because if the Mets are going to be halfway decent in 2012, its going to be because of their pitching staff, not the offense. And as Mets fans know all to well, a starting pitcher can't earn a win if the closer blows the lead in the ninth.

Ryan Madson, Philadephia Phillies

I realize it would be tough for Mets fans to have to root for a player they have hated on the Phillies for years, however, should the Mets sign Madson, it would be worth the heartache. Madson is a hard-throwing reliever who has morphed himself into a closer after filling in for Brad Lidge during his battle with injuries.

Madson would be an amazing fit for the Mets because he wouldn't command as much money as other free-agents on the market and he is right in the middle of his prime at 31 years old.

Madson has the potential to become one of the best closers in the MLB should he come to New York, as Citi Field's dimensions are much more pitcher-friendly than the Phillies' Citizens Bank Park (but not as much as it used to be).

The only problem is that he may be hard to pry from the rival Phillies should they not sign a different free agent closer this offseason. Overall, a very solid closer who is used to being on winning teams, you can't really ask for much more in a free agent candidate.

Heath Bell, San Diego Padres

Definitely the cream of the 2011 free-agent closer crop, this former Mets farmhand truly is one of the best closers in the game right now and definitely the best free-agent.

Bell started his career after being signed as an undrafted free agent by the Mets in 1998 and was later traded to the Padres in another lopsided deal that turned out poorly for the Mets. Bell is a shut-down closer and managed to earn 43 saves last season on a 91-loss Padre team.

He would be a great pick-up for the organization and I'm sure Heath would love going back to where his professional baseball career started and play half of his games in an even pitcher-friendlier ballpark in Citi Field. The only problem with Bell and the Mets is money.

Coming off his stellar year with San Diego, he is sure to command a lot of money with some big-market teams looking for closer help (Dodgers, Red Sox, Cubs). Who knows, maybe Alderson could work some small discount plan out with Bell in order for him to return to where it all started.

Conclusion: The Mets Should Go with Nathan

All things considered, the Mets should probably make the biggest push for Nathan. He is one of the most cost-effective closers on the open market this season, he is familiar with the New York area and let's be honest, most people like coming home.

Also at his veteran age of 39, Nathan and his agent will only be looking for a three-year deal to finish out his career.

That would work perfectly for the Mets as three years will probably be enough time for the closing prospects in the Mets' farm system to develop and become major-league ready.

Nathan also provides tons of experience and veteran leadership that simply isn't in great supply in the clubhouse right now. He also has pitched in the post-season which is invaluable experience especially on a relatively young team like the Mets.