Casey Janssen. (Photo by Katherine Frey/The Washington Post)

When the Nationals signed Casey Janssen to a one-year $3.5-million deal that included an option for 2016, they believed the former closer’s track record would enable him to be a solid replacement for traded Tyler Clippard, and to fill the needs of a new-look bullpen. Instead, Janssen’s past shoulder issues flared up, he missed most of the first two months of the season and then endured his worst major league season since 2009.

Although some of his peripheral pitching statistics weren’t much different than his 2014 season, Janssen did worse, a 4.95 ERA in 2015. His hits, home runs and walks allowed were above the marks in his best seasons, and his strikeout rate was below his career rate. At key times, the 34-year-old struggled to put batters away, his 88.3 mph fastball the lowest average of his career.

So now the question is: Do the Nationals, who will need to overhaul their bullpen in the offseason, bring back Janssen? The option for 2016 is for $7 million, and a mutual one, meaning both sides have to pick it up to trigger it. If not, Janssen is owed a $1.5 million buyout, which is the all-but-likely outcome given his struggles this season.

“I don’t know how it’s going to go,” Janssen said in the waning days of the season. “If you want to get deep into the things, you can make a case either way. Some of the tough games I had I probably wasn’t bringing out my A stuff. And I think there was a stretch where myself, and not only myself but a lot of us down there, were used often. At the same time, we didn’t have the ability to have those days off when we could have used them to have been 100 percent or be in your tip top form. You just had to go out there and bring whatever you had to the mound and hopefully it was good enough to get three outs.

“Unfortunately in those situations, it wasn’t for me. I made my bed so I have to sleep in it. Whatever happens happens. I’m just ready and excited to look at what the future holds. If it’s Washington, I’ll come back here in a second. If it’s a new chapter in my career, I did it once and I came to a pretty great team and met a great group of guys, and I’ll just have to do it again.”

Despite the down season, Janssen said his confidence is great. He has never relied on velocity, even in his best seasons, but any loss increases the margin for error. In an age of hard-throwing relievers, it is hard to survive with 88 mph fastballs unless command is always spectacular. And in Janssen’s case, his mistakes were hit harder and more often in the air than before.

“There’s no doubt in my mind I’m gonna have a great season next year,” he said. “You take out the three or four games that I didn’t pitch my best I had a solid year after that. Obviously you can’t take those away. Those are real. But, there’s no doubt in my mind that the passion is there and the ability is there. There’s going to be a ton of drive there for me this offseason to not let that happen again and get back to what I know and get back to be the pitcher that I know I can be.”

As a whole, the Nationals bullpen was a weakness for large parts of the season and reared its ugly head the most in key situations, especially in the second half when every loss was more painful. A consistent bridge from the starter to the back end of the bullpen was hard to find. The seventh inning, where Janssen often operated, was a frequent stumbling point. A year after finishing second in the NL in bullpen ERA, the Nationals finished sixth, which may not sound like much until you realize they gave up 24 more runs in the exact same number of innings.

The Nationals hoped Janssen would fill Clippard’s spot, but he was injured to start and they scrambled to fill that role, even using Blake Treinen, who wasn’t ready for a set-up role. Xavier Cedeno didn’t pitch well, was misused and let go. Then versatile and consistent Craig Stammen got hurt, and the Nationals turned to more young relievers. Only Felipe Rivero proved to be the most reliable of the rookies. The bullpen’s struggles were further proof of how indispensable Clippard and Stammen were, and showed that the Nationals counted on too many young relievers.

“It was frustrating,” Janssen said of his own season. “Starting off in spring training and having that little hiccup. Obviously you work your butt off in the offseason to be healthy and start the season. It was unfortunate. Then getting into the season. Other than the first game, the Cincinnati game, I thought I was doing pretty well. Obviously the big circle on my season was the two games in St. Louis. It was a tough stretch for me there. It was a time when the season was at that kind of turning point. I didn’t get it done. There were probably some reasons why. But it just didn’t happen. From there, it kinda was a part of that spiral we were in.”