WASHINGTON - Late in the winter the past two seasons, when it appeared their roster was already set, the Washington Nationals made one final significant, surprising addition. In February 2012, they added Edwin Jackson to a full rotation. Last January, the Nationals dropped Rafael Soriano into the stuffed back of their bullpen.

Even if the Nationals knocked out most of their work early in this offseason, could they have one more move - or a series of moves - left? Over the weekend, Ken Rosenthal of Fox Sports reported that the Nationals have shown interest in free agent reliever Grant Balfour, the fiery, 36-year-old Australian who saved 38 games for the Oakland A's last season.

Though on the surface the Nationals' bullpen seems to be well-stocked, with Soriano still under contract through 2014 after he saved 43 games last year, the potential interest in Balfour makes sense on several levels. Speaking on MLB Network on Tuesday morning, Nationals General Manager Mike Rizzo certainly did not refute Rosenthal's report.

"At this time of year, we're looking at any way to improve our ballclub," Rizzo said. "Sometimes, you get some values at this time of year. We're looking for any way to strengthen a weakness we have. We feel our bullpen is extremely strong. It's a big part of our ballclub. But if we could strengthen a strength, that never hurts, either. You can never have too many good players. Especially in January, you can never have too many good arms, too many starters, too many relievers. We're looking at every avenue. We leave no stone unearned. If you can find a value and improve your ballclub, strengthen a strength, we're all for it."

If you're into reading tea leaves, Rizzo also dropped the "strengthen a strength" term last year to explain his rationale for signing Soriano.

We should know soon how serious the Nationals' interest in Balfour is. Balfour is expected to make his decision within a week, if not the coming days, according to a person close to the situation.

The Nationals have shown signs of making one more key acquisition. Their desire to sign Jordan Zimmermann and Ian Desmond to two-year deals hinged, in part, on the structure of the contracts. Both are back-loaded, and each player will make less in 2014 than he likely would have through an arbitration hearing resulting in a one-year deal. Ultimately, the two-year deals allowed the Nationals to clear about $3 million off their 2014 payroll.

Soriano's contract status would also provide motivation to add another reliever capable of pitching the ninth inning. When Soriano signed last winter, his two-year contract included a $14 million option for 2015 that vests if he finishes 120 games over both seasons. Soriano had 58 games finished last year. The Nationals surely do not want Soriano to finish 62 games and activate the option.

Balfour would add another layer of experience to a bullpen that ranked in the middle of the pack in most statistical measures. He has played on contenders for almost all of his career, spending the last six seasons with the Rays and A's. Over those six years, Balfour has a 2.74 ERA. He has shown little sign of slowing down; Balfour made his first all-star team last year, threw his fastball 93.4 mph and struck out 10.3 batters per nine innings.

Balfour could both lessen Soriano's load and provide insurance in the ninth inning. Soriano converted 43 saves in 49 chances, an excellent ratio. But many of those saves came in excruciating fashion, and he slipped in several tell-tale areas. He struck out 6.89 batters per nine innings, down from 9.18 in 2012. His averaged fastball dipped from 92.3 mph to 91.4.

If the Nationals added Balfour, it could lead to a trade, perhaps of Drew Storen, who will make $3.5 million in 2014. The bullpen already includes Soriano, Tyler Clippard, Craig Stammen, Jerry Blevins, Ross Ohlendorf, Xavier Cedeno, Ryan Mattheus and other candidates. But trading Storen now may be selling low on the 10th pick of the 2009 draft. Despite an excellent rebound in the final month and a half, Storen struggled so much last season he was briefly demoted to Class AAA Syracuse.Balfour agreed to a two-year, $15 million contract with the Orioles in December, but the deal fell apart after the Orioles claimed Balfour failed a physical. Balfour's agent released a statement excoriating Baltimore, claiming the Orioles simply changed their mind.