There's no way Roark should have pitched in the 8th. First, look at the quality and where the team is in the lineup. If you're at 6-7-8 or 7-8-9 of a fairly weak lineup, you can give the pitcher a little more leeway, with a big lead. This was the lineup of the defending WS champions.
For Roark, they were at 9-1-2 and when they got back to leadoff, that was the beginning of the 4th time through the lineup. When did Tanner Roark become a pitcher who should be allowed to be seen by a lineup, four times? Answer, he's not. There are few starters who should see a lineup four times and the Nationals don't have any of them. And it wasn't as if Roark had been putting up zeros. He's already given up three runs.
This was botched just as much as how long he stayed with Papelbon.