What to expect from the two new relievers (roster moves official)

The Nationals will have two new faces in their bullpen tonight when they take on the Giants in game two of this three-game set in San Francisco. Well, one of the faces will be new. To those who have followed the Nats for a few years now, the other should be familiar. Right-hander Yunesky Maya and left-hander Fernando Abad will be activated by the Nats prior to tonight's game out west. Maya, who signed a four-year, $6 million deal with the Nats in 2010, has appeared in 15 games (10 starts) with the Nationals at the big league level, posting a 5.52 career ERA. He last appeared in the majors in 2011, registering a 5.23 ERA over 32 2/3 innings. This season at Triple-A Syracuse, the former Cuban defector has a 5.07 ERA in eight starts, although he's allowed just four earned runs and struck out 16 over his last three outings, spanning 20 2/3 innings. With both Zach Duke (58 pitches) and Craig Stammen (46 pitches) getting a heavy workload yesterday, Maya will serve as the Nats' long reliever for the time being. He was already on the 40-man roster and is on normal rest today, so he was an easy choice to fill this role for now. Maya's stay with the Nationals might not be a long one. Once the bullpen has gotten all its guys back rested, and assuming Ross Detwiler is able to make his next start after dealing with a slight oblique strain, Maya would likely be optioned back to Triple-A so that the Nats can go back to having a five-man bench. Abad, however, has a chance to stick with the big league club a bit longer. The 27-year-old left-hander, signed to a minor league deal this offseason after spending the last seven years in the Astros' system, really impressed in spring and has been tearing it up at Syracuse. In 17 games at Triple-A, spanning 17 innings, Abad has a 1.06 ERA, 1.118 WHIP and 12 strikeouts to just two walks. He has yet to allow a home run this season and has not been scored upon in his last seven appearances. Abad pitched well enough in spring training that he had a chance to crack the Nats' 25-man roster to open the season. Manager Davey Johnson was determined to give the left-hander a long look and liked what he saw. When the Nats opted to carry Duke as their lone left-hander in the bullpen, however, Abad was ticketed for Triple-A. Johnson has mentioned multiple times already this season, however, that he feels his bullpen is unbalanced and has inferred that he would prefer to have another lefty - more of a situational southpaw - in the 'pen for use in the late innings. If Abad is able to carry over his Triple-A effectiveness to the major league level, he could be up here for a little while, with Ryan Mattheus likely to miss upwards of a month because of a broken right hand. Update: The Nats have officially placed Ryan Mattheus on the 15-day DL, retroactive to May 20, with a fractured right hand and optioned outfielder Eury Perez to Triple-A Syracuse. Maya and Abad will take their places on the 25-man roster. Mattheus has a 4.96 ERA in 14 relief appearances this season, while Perez went 0-for-5 in five games with the Nats after being recalled on May 11.