The Washington Nationals selected the contract of right-handed pitcher Abel de Los Santos from Double-A Harrisburg on Monday and optioned right-handed pitcher Blake Treinen to Triple-A Syracuse. Left fielder Jayson Werth was transferred to the 60-day disabled list to clear space for de Los Santos on the 40-man roster.

de Los Santos, 22, is 4–4 with a 2.65 ERA in 26 appearances (31.1 IP) for Double-A Harrisburg this season. The Dominican Republic-native has not allowed a run since June 8 — a 15-inning stretch (nine appearances) in which he has held opposing batters to a .104 average and struck out 15.

The hard-throwing right-hander has struck out 8.4 batters per nine innings this season in the Eastern League (career K/9: 9.1) and has posted a 0.884 WHIP. He has allowed only nine extra-base hits (7 doubles, 2 home runs) and walked just eight while striking out 35.

de Los Santos was acquired from the Texas Rangers, along with second baseman Chris Bostick, in exchange for left-handed pitcher Ross Detwiler on Dec. 12, 2014.

Though he made eight appearances to begin 2014 with Single-A Hickory of the South Atlantic League, de Los Santos spent the majority of his season with Single-A Myrtle Beach (33 games), where he was 5–2 with a 1.97 ERA. Signed out of the Dominican Republic by the Rangers in 2010, de Los Santos worked to a 0.959 WHIP and struck out 10.4 batters per nine innings in 2014.

Treinen, 27, is 2–2 with a 4.39 ERA in 32 appearances (41.0 IP) out of the Nationals’ bullpen in 2015. His 44 strikeouts rank 16th in the National League and he has walked 21 batters this season.