A career 67-83, Pérez has made 195 Major League starts, finished 58 MLB games, worked to a 4.44 ERA and worn the Major League uniform of six different teams: San Diego (2002-03), Pittsburgh (2003-06), New York (2006-10), Seattle (2012-13), Arizona (2014-15), and Houston (2015). He returns to the National League East at the big league level for the first time since a five-year stint with the Mets, in which he went 29-29 with a 4.71 ERA and amassed 520.0 innings pitched.
Over the course of his career, Pérez has held left-handed batters to a .238 average, but he was exceptionally tough on left-handed batters in 2015, holding them to a .185 average and .235 on-base percentage. Last season, with the Diamondbacks and Astros, Pérez struck out 34 percent of all left-handed batters he faced (98) and issued only five walks.
Pérez is one of only five left-handed relievers across the Major Leagues who has appeared in 60 games or more and struck out at least 50 batters in each of the past three seasons, joining Tony Watson (PIT), Glen Perkins (MIN), Mike Dunn (MIA), and Brett Cecil (TOR). In his career as a reliever, he's kept 70.1 percent of inherited runners from scoring, and accrued 25 holds over the previous two years.
The left-hander has made four postseason appearances, separated by nine years, as he started twice in the 2006 National League Championship Series for the Mets and appeared in two games this past October for the Astros in the American League Division Series.
Pérez, 34, was signed as a non-drafted free agent out of Mexico by the San Diego Padres in March, 1999. A three-time member of the Mexican World Baseball Classic team (2006, 2009, 2013), Pérez made 188 MLB starts from 2002-09, including the final home opener (April 8, 2008 vs. PHI) and the final game (Sept. 28, 2008 vs. FLA) at Shea Stadium.
With the addition of Pérez, the Nationals currently have 38 players on their 40-man roster.