Should there be concern over bullpen overuse in just third game of the season?

The bullpen struggled in the season-opening series with the Mets. In the eighth inning alone, the Nationals 'pen allowed eight runs on 11 hits in the three games combined.

On Sunday, the Nats relinquished a 5-2 lead, but rebounded in the end thanks to a dramatic walk-off solo homer by Trea Turner to salvage the final game of the series with a 6-5 win.

After Patrick Corbin pitched six innings, Justin Miller got through the seventh without allowing a run. But in the eighth, the Mets scored three runs on four hits to tie the game. Left-hander Tony Sipp allowed two runs on two hits, recording only one out.

Robinson Canó singled to begin the rally. After Sipp got J.D. Davis to pop out to second base, Michael Conforto singled. Sipp was lifted and Trevor Rosenthal that allowed an RBI single to Amed Rosario on one pitch to make it 5-3.

Closer Sean Doolittle struck out Keon Broxton. However, pinch-hitter Wilson Ramos and Juan Lagares both dropped in run-scoring singles to tie the game at 5-5.

Sipp, who pitched for the second straight game, felt like he stayed on his game plan, but the Mets just were able to make enough contact to push through base hits.

"From my point of view, feel like I hit spots," Sipp said. "Kind of kept them off-balance. Canó was first pitch, but I felt like I had a game plan trying to get in there. But for the most part, I feel soft contact like that, that's kind of the goal. But obviously, you want results. It's one of those things where you go in there you try to take the positives out. Didn't get the results, but I didn't make mistakes on my end. Something to build off of."

On Saturday, Sipp pitched a scoreless seventh with a walk and one strikeout. But Sunday didn't work out to his liking. But this might not be fair to the southpaw, who was signed late in spring training to shore up the left side of the bullpen. Sipp admitted he still has some catching up to do and his velocity is not quite at the level he wants it to be quite yet.

"It sucks. It sucks not getting the results," Sipp said. "But I can't hang my head. Still got a lot of question marks of how I'm feeling and everything. Really, I'm just battling myself. All I can do is hit my spots with whatever I do have. I try not to get caught up and be too result oriented, but have a good approach and try to execute a plan and help the team win."

Manager Davey Martinez was asked if he considered staying with Sipp and Rosenthal even though they allowed key base hits. Martinez reasoned that he did not think the pair were taxed too much and the plan was for Rosenthal to face one batter because he pitched Saturday, too.

"It was about pitch count with those two guys," Martinez said. "Sipp has only had, that's his fourth inning in a couple months. So for him to be available and say he is available today, that's pretty awesome. And also Rosenthal, his first time back-to-back, I didn't want him going out there throwing a lot of pitches, I wanted him to try to get that one out.

"And they pitched. ... I really believe, we want to get outs, I get it, and the Mets have done their job by putting the ball in play. But we made some pretty good pitches and they have just been getting them hits."

Doolittle made his season debut in an unusual situation. He had to pitch multiple innings when normally he needs to gets just three outs in the ninth. The closer replaced Rosenthal with one out in the eighth Sunday and allowed the Ramos and Lagares singles, both just over Trea Turner's head and glove and into left-center field.

"Whenever you come in with men on base, the key is the first guy, getting the first guy out," Doolittle said. "I was able to do that and after that, unfortunately, a couple of those hits dropped in. The first one seemed like it hung up there forever. That kind of happened in slow motion. But I think in both cases I made pitches I wanted to make. Neither ball was hit hard. Unfortunately, sometimes in those situations, you have to catch a break and get a little bit lucky."

Doolittle wasn't concerned that the two base hits signaled a more serious problem with the potency of his pitches. He said it was just plays that didn't go his way. On the Ramos single, Turner appeared to almost get to the ball for the catch, but it bounced away at the last second.

"There's only so many things that you can control," Doolittle said. "Unfortunately, they got just enough of those to drop them in. Then it becomes a situation where you want to bend and don't break and give your team a chance. Not give up the lead entirely to a point where you come off the field (and) now you're trailing. So keep it right there. That's a tough first one, but that's the life of a reliever getting thrown right into the fire."

But the bullpen has suddenly been placed in a difficult spot in just the third game of the season. Relievers have been used a lot because they haven't been able to finish off innings. It is especially demoralizing when the starters have each been able to go at least six innings apiece.

Doolittle said it's not that the taxed bullpen that was his team's concern from Sunday's series finale. He said the bottom line was the Nats had to have this win and were willing to go all out with the 'pen to reach that goal.

"I think it's a combination of knowing we have an off-day tomorrow and having dropped the first two games of the series," Doolittle said. "We were going all-in today. We were pushing our chips into the middle of the table. We wanted to play the matchups right there. Matchup with the lefties and the righties middle of their order.

"At the time, that was the biggest inning of the game. Those were the biggest outs for us in the game. So just trying to match up. We feel like we have the weapons to do that. Unfortunately, it just didn't work out."

But did the Nationals make a mistake in setting their bullpen for the start of the season? Sipp admitted he's trying to get back up to speed in season. The club has not used fifth starter Jeremy Hellickson in the bullpen even though he is not slated to start a game until April 10 at Philadelphia.

"Yeah, I mean, we're going to address a couple of things, but look, ... we got a day off tomorrow, and we're just now getting out of March," said Martinez. "But I expect these guys to be ready to go again on Tuesday. We need to say, Pat Corbin pitched really, really well, so we come back Tuesday and we got (Max) Scherzer on the mound, so here we go."