This was the second time in a week that Mattheus had problems with his pitching shoulder. Last week, he hurt it while lifting weights. This week's injury was unrelated; in Thursday's game against the D-backs, Johnson realized that Mattheus' velocity was down, and he was immediately taken out of the game after facing two batters.
Johnson pointed out that the Nationals are not in a pennant race, so there isn't any need to rush Mattheus back to the field. Mattheus has become one of Johnson's most reliable relievers, appearing in 32 games with a 2.40 ERA, mostly in the late innings.
"We are not fighting for a playoff spot," Johnson said. "He is too good a young pitcher. His future [is something] we are going to protect. He is going to be on the DL for a couple of weeks. He may not pitch the rest of the year. Then again, he may be fine after a little rest, and then pitch."
Mattheus said he understood why Johnson wanted him take a break.
"He said, 'We are going to be cautious, we are going to take our time,'" Mattheus said. "There is no reason to push it. He wants me to be honest and let him know what's going on -- communicate well with him. We are looking to the future, not really right now. It's not worth getting injured again."
The Nationals are not expected to make a corresponding move until Saturday, but according to two sources, they will promote first baseman Chris Marrero from Triple-A Syracuse.
Marrero, who is hitting .300, with 14 home runs and 69 RBIs, will get starts starts at first base, while Michael Morse will see action in left field.