Updated at 4:03 p.m.
Willingham, who hit .268 with 16 homers and 56 RBI in 114 games this season before undergoing knee surgery in August, was due to become a free agent at the end of the 2011 season, and the Nationals had not shown interest in re-signing him to an extension. Several teams inquired about the 31-year-old's availability at last week's Winter Meetings in Orlando, including the A's and Red Sox.
As currently constructed, the Nationals will likely use a combination of Roger Bernadina and Michael Morse in left field. Team officials have long believed Bernadina, who hit .246 with 11 homers and 47 RBI in 134 games as a rookie, is best suited defensively to play left field. Morse, who hit .289 with 15 homers and 41 RBI in 98 games, could serve as a right-handed platoon with Bernadina in left field and also see some time in right field, at first base and off the bench.
Both players the Nationals acquired in the deal could see time in Washington this season.
Rodriguez, a hard-throwing right-hander, did appear in 29 games for Oakland over the last two seasons, posting a combined 4.26 ERA while striking out 37 in 31 2/3 innings. The 23-year-old reliever (who threw a 103 mph fastball this year) has notched incredibly strong strikeout numbers in the minors and has struck out 27 batters in 20 1/3 innings this winter pitching in his native Venezuela.
Brown, the 59th overall pick in the 2007 draft, is a gifted center fielder who hit 30 home runs in Class A in 2008 and then hit .320 at Class AA last season before seeing his batting average drop to .193 in 41 late-season games at Class AAA. The 25-year-old probably needs more seasoning but could be a potential long-term answer in center field for the Nationals.
Both Rodriguez and Brown were on Oakland's 40-man roster and thus are transferred to the Nationals' 40-man roster, which is for now completely full with the completion of this trade.