WASHINGTON -- Chris O'Grady spent most of Tuesday afternoon in the training room receiving treatment on the right oblique he strained Monday. While the Marlins are waiting for the doctor to tell them how severe O'Grady's injury is, manager Don Mattingly expects him to miss significant time, and they sent the rookie lefty to the 10-day DL on Tuesday. Reliever Javy Guerra will replace him on the active roster. 
Mattingly said O'Grady's timetable is similar to Justin Bour, who hasn't resumed baseball activity since straining his right oblique July 25.
"You can't throw during any of this," Mattingly said. "A regular oblique for a pitcher, it's going to take a while. It's going to take a pretty good chunk of the season for him."
Mattingly said Odrisamer Despaigne, who replaced O'Grady on Monday vs. the Nationals and allowed one run over 3 2/3 frames, is an option to start in place of O'Grady on Saturday. The right-hander has started 35 Minor League games, including 10 with Triple-A New Orleans this season.

The Marlins' rotation currently consists of Dan Straily, Jose Urena, Adam Conley and Vance Worley with Edinson Volquez and Wei-Yin Chen sidelined.
The Marlins' bullpen has pitched the second-most innings in the Major Leagues this season, and it'll probably be relied on more with O'Grady on the shelf. So, the Marlins promoted Guerra, who notched a 4.99 ERA in 33 appearances this season with New Orleans.
The right-hander has played 153 Major League games, including seven last season with the Angels. But the 31-year-old has never appeared in more than 47 Major League contests in a season, and hasn't played more than seven games since 2014, when he held a 2.91 ERA in 42 appearances with the White Sox.
"I've been working on a lot of stuff," Guerra said. "Really just fine-tuning a bunch of stuff and making it really good, just [working on] a couple good things as opposed to a bunch of mediocre things. Consistency and really just going back to the old things I did well and attacking guys."