The Nationals' 27-year-old right-hander started the game with a 0.68 ERA, 11 walks (2.48 BB/9) and 31 Ks (6.98 K/9) over 40 IP in Nationals Park since his debut last August.
Roark threw three scoreless to start the game, but surrendered two runs in the fourth inning when Reds' shortstop Zack Cozart doubled and scored on an RBI single by Brandon Phillips and Phillips then took second on an error by Kevin Frandsen and third on a fly to center by Todd Frazier before scoring on a one-out single to left field by Brayan Pena.
The two runs gave the Reds a 2-1 lead which right-hander Alfredo Simon maintained through seven innings of work on the mound over which he gave up just five hits and one run on a first inning home run by Denard Span.
The Nationals had their chances against Cincinnati's 33-year-old right-hander, who started the game (4-0) on the road in 2014 with a 0.99 ERA, nine walks (2.96 BB/9) and 21 Ks (6.91 K/9) in 27 1/3 IP outside of Great American Ballpark.
The Nats were 0 for 5 on the day with runners in scoring position, however, as both Simon and the Reds' bullpen shut the down, allowing Cincinnati to take two of three in D.C.
The Nationals were up 1-0 when they put the first two runners on with no one out in the second. They loaded the bases with one down before Roark grounded into an inning-ending double play.
With the Reds up 2-1 in the sixth, rain delayed the game for an hour and one minute, after which Nats' skipper Matt Williams made the decision to bring Roark back out with two down so he could try to get his pitcher a win if the Nationals were able to rally.
They didn't though, and after a scoreless bottom of the sixth by Simon, Roark was replaced.
"We had our chances to tie it certainly," Williams said after the loss when asked about sticking with Roark, "and an hour plus rain delay and going back out there to finish that inning and try to get him a win or at least a no-decision. So, he pitched really well. He stayed loose and was able to go back out there."
Roark told reporters, including CSNWashington.com's Chase Hughes, that he stayed loose by simulating the up and down nature of resting between innings:
Roark on staying loose during delay: 'Since it was an hour, I would go 10 to 15 pitches every 10 to 15 minutes.' #Nats— Chase Hughes (@chasehughesCSN) May 22, 2014
"It's one thing to get him if he's got to go a full inning or inning plus," Williams explained, "but he's got two outs in that inning and we wanted to give him the opportunity to tie the game in the bottom of the inning there at least."
The Nationals' first-year skipper said he was comfortable sending Roark back out.
"It depends on how he feels," he said. "Simon went out there too and he actually had a longer delay than Tanner because he was in the middle of an inning, so it all depends on how they feel and how well they can stay loose during the delay."
"It all depends on how they feel and how much they can stay loose during that time," Williams continued. "They've got to kind of simulate innings. Not necessarily going full bore, but get up, sit down, do all that stuff during the delay to try to see how they are. But he went out there and pitched."
So did Simon, who gave up just one hit in the two innings of work after the delay. Williams said the Nationals' hitters had a tough time against the Reds' right-hander.
"Multiple arm angles," Williams said when asked why Simon was difficult to face. "He's a tough matchup for right-handed hitters anyway. He drops down with his slider and his fastball, mid-90s fastball too. So he's good. He's been pitching well for them."
Through eight starts, Simon limited right-handed hitters to a .217/.258/.337 line.
Williams wasn't, however, willing to blame the Nationals' offensive struggles on the Nats' injury-riddled roster.
"It is what it is," he said. "We can't do anything about it. So we want those guys back as quickly as possible, but our guys are capable too."
The losses in two of three game against the Reds were to two pitchers who put together strong starts.
"It's a product of who we're facing too," Williams said. "Leake's a quality pitcher too. And we beat a good one last night too."
The Nationals' one win of the series came against Johnny Cueto, who took the mound on Tuesday with the lowest ERA in the majors and gave up six hits and eight runs, six earned in his shortest outing so far in 2014.
The Nationals took two of three from the New York Mets and dropped two of three to the Reds. Up next, a four-game series with the Pittsburgh Pirates on the road in PNC Park.