The Nationals announced that they designated left-hander Atahualpa Severino for assignment. The move creates 40-man roster space for Cesar Izturis, who was claimed off of waivers from Milwaukee. The Nationals created room for Izturis on the 25-man roster by placing Mark DeRosa on the 15-day disabled list.
Severino appeared in six games on last year's Nationals team, but has spent the entire 2012 campaign at Triple-A Syracuse. The 27-year-old has a 2.72 ERA with 8.2 K/9 and 6.3 BB/9 in 40 relief appearances so far this year. He has generally had high strikeout and walk totals in his seven-year minor league career: 9.3 K/9 and 4.2 BB/9.