Heyman says the Nationals will pay Hairston's contract and performance bonuses this year, while the Cubs will chip in less than $500,000 next year.
This season, the 33-year-old Hairston is batting .172/.232/.434 in 112 plate appearances. For his career, he owns a slash line of .244/.299/.448 across parts of 10 major-league seasons. Hairston is capable of playing all three outfield positions.
The right-handed-hitting Hairston also fills a tactical need for the Nationals, who this season have been one of baseball's least effective offenses against left-handed pitching.
The Cubs are projecting that prospect Junior Lake will be their righty-hitting platoon outfielder next year.
UPDATE: The Cubs will receive 21-year-old right-hander Ivan Pineyro in the trade. He has a 3.24 ERA with an 8.3 K/9 and 3.27 K/BB in 77 2/3 innings across 15 starts for two Single-A affiliates this year.
Baseball America ranked Pineyro as the Nationals' 27th-best prospect before the season in their 2013 Prospect Handbook.