Rosenbaum was reassigned to minor league camp Monday, Pete Abraham of The Boston Globe reports.

Rosenbaum, who started 15 games in Boston's organization last season, will be used as a reliever in 2016, the Boston Globe reports.

Rockies returned Rule 5 LHP Daniel Rosenbaum to the Nationals. Rosenbaum allowed four runs and didn't record any strikeouts over eight innings this spring for the Rockies. The southpaw could start the season at Triple-A.

Rule 5 selection Daniel Rosenbaum was very impressive in his Rockies debut on Friday, allowing just one hit over two scoreless innings in a victory over the Brewers. The 25-year-old left-hander made a good first impression in his bid to crack the Rockies Opening Day roster. He registered a 3.94 ERA, 1.31 WHIP and 99/39 K/BB ratio over 155 1/3 innings for the Nationals Double-A affiliate in 2012. He's unlikely to carry any fantasy value in 2013.