He's a quality back end starter. The Nats have one arm too many, which is a shame since he probably won't make the postseasn roster. Then again, he'll get contenders the rest of the season, so he may just yet earn a spot.
I think he'll make the post-season roster. He'll be a long man out of the pen and spot starter if games get bunched up due to rainout(s) and a 5th starter is needed. Detwiler was the 5th starter until last week and he surely would have made the post-season roster in that role if Stras was still pitching.