Lefty bullpen guy(s) for right-handed bullpen guys

[Nationals]

Simple situation here: I have a good number of left-handed bullpen arms. I'd like to shore up my right-handed supply by swapping one of these guys out. I'm looking for a one-to-one swap. Similar stats/age for similar stats/age (so don't come around offering a 35 year old groundballer for a 25 year old strikeout arm).

The offerings (all stats are ZIPs for 2015):

Jerry Blevins, 31 years old, 114 ERA+, 8.73 K/9
Dan Jennings, 28 years old, 106 ERA+, 8.69 K/9
Andrew Oliver, 27 years old, 104 ERA+, 11.71 K/9
Brian Duensing, 32 years old, 92 ERA+, 7.13 K/9

[Nationals]

And that need has been filled. Thanks!