By Tommy Rancel //

When the Nationals acquired Josh Willingham and Scott Olsen from the Marlins in exchange for Emilio Bonifacio and a pair of minor leaguers before the 2009 season, it was Olsen who was thought of as the key player in the deal. After all, he was a 24 year-old left-handed starter who had made at least 30 starts in each of the previous three years without a trip to the disabled list.

Willingham was a throw-in perhaps, a soon-to-be 30 year-old serviceable outfielder with some okay offensive numbers. Marlins President of Baseball Operations, Larry Beinfest admitted money was one of the reasons the deal was made as both players were entering their first year of arbitration.

Things turned out a little differently. Although he escaped the DL in Florida, Olsen has been bit by the injury bug in Washington. He has made just 19 starts since the trade – tossing 105.2 innings with a 4-6 record in two seasons. On the other hand, Willingham has become one of the best offensive players in the National League no one is talking about.

After posting a more than respectable slash line (AVG/OBP/SLG) of .260/.367/.496 with 24 home runs, 61 RBI and 70 runs scored in 2009, Willingham is turning in his best work in 2010. The former catcher is hitting a modest .273; however, he is slugging .502, and is getting on-base at a .405 clip. Both would be career highs for a full-season.

Whenever a player has a breakout season beyond the age of 30, some will assume it is a fluke or an outlier. In a lot of cases this is true. That said, Willingham is on a steady four-year OPS incline suggesting that he maybe nearing – or right at – his career peak.

If you are looking for fluke stats – good luck. His batting average on balls in play (BABIP) of .295 is lower than his career .299 number. His ISO (Isolated Power), which indicates raw power by taking slugging percentage and subtracting batting average, is .229, or within 15 points of his career .215 average.

The biggest change for Willingham in 2010 is better plate discipline. He is walking 15.8% of the time (up from 11.5% career), and is striking out slightly less (22.1% in 2010, 23.1% career).

Despite the .907 OPS and a .403 weighted on-base average (wOBA), an advanced metric that measures multiple offensive numbers and is scaled to mirror OBP, “The Hammer” is only owned in 55% of leagues according to hotboxsports.com.

Because of his age and contract status (one more year of arbitration), Willingham could be a trade candidate in both leagues should the Nationals choose to sell. That would make him a slight risk in NL-Only formats. Nevertheless, there is no reason to wait on grabbing him off of waivers – if you’re lucky enough – or through a trade in mixed leagues right now.

For more on Josh Willingham and other breakout candidates, check out Bloomberg Sports Fantasy Tools