Avilan has played for the Atlanta Braves, Los Angeles Dodgers, Chicago White Sox, and Philadelphia Phillies during his seven-year career. The 29-year-old left-hander sports a 3.09 ERA, a 3.25 FIP, a 21.5% strikeout rate, and a 9.2% walk rate in 308.2 career innings out of the pen. Last season, he posted a 3.86 ERA and 2.71 FIP in 39.2 innings with the White Sox (0.9 fWAR) before being dealt to the Phillies in August. He made 12 appearances for Philadelphia and finished with a 3.18 ERA and a 5.81 FIP (-0.1 fWAR).
Avilan has been successful in his career against left-handed batters, and that trend continued in 2018. Against 93 batters, he allowed 18 hits, which amounted to a .220 batting average against and a .646 OPS while striking out 25.8% of opposing lefties. Righties, on the other hand, hit .280 with a .733 OPS against him in 104 at-bats while striking out at a similar clip.
With the additions of Avilan and Santiago, it appears the Mets are content to fill their lefty void in the bullpen with these low-risk signings. In addition to the two newly-acquired relievers, the club will likely take a look at Daniel Zamora during spring training in an effort to replace Jerry Blevins as the primary left-hander in their bullpen.