Marty Niland: How does the Melancon trade affect the rest of the Nats bullpen?

So the Nationals have finally landed a new closer, with Mark Melancon coming from Pittsburgh. General manager Mike Rizzo sent left-hander Felipe Rivero and prospect Taylor Hearn to the Pirates in hopes that he can solve the late-inning issues that have plagued the team in the past week.

But what will become of the man he's supplanting, Jonathan Papelbon, and the rest of the bullpen? Papelbon is on record as saying he is OK with the move, despite the fact that his new role is undefined. When Papelbon arrived as the team's closer a year ago, he displaced Drew Storen, who also said all the right things, but obviously had trouble accepting his role as a set-up man. After a few sharp outings, Storen's performance deteriorated and he proved incapable of getting outs in high-leverage situations.

Will Papelbon follow in Storen's footsteps? Can he be trusted as a set-up man? Manager Dusty Baker had him warming in the bullpen with the Nats trailing in the bottom of the eighth, indicating that he might have come into the game had Sammy Solis gotten into trouble. So perhaps he will become a situational right-hander or mop-up man.

Aside from his closer, Baker has played specific bullpen roles close to the vest. In fact, some of the decisions he has made in the past week or so have been curious, including using Papelbon in four successive games, including three days in a row against San Diego in non-save situations.

But with all their troubles in the past week, the Nationals still have the second-best bullpen ERA in the National League and the third-best in all of baseball at 3.08. Their 1.19 WHIP is third in the NL. They still have the pieces to hold a lead for the stellar starting staff. Keeping in mind that one of the pitchers might be sent to the minors when starter Joe Ross returns from the disabled list, here's how they break down.

Right-hander Shawn Kelley seems best suited to keep his role as set-up man. Despite allowing back-to-back homers to allow San Diego to tie last Sunday's game in the eighth, he has been the team's most effective reliever with a .224 batting average against and a 1.02 WHIP. His main concern is the fact that he's had two Tommy John surgeries, and Baker has said he's wary of overusing him.

Righties Blake Treinen and Matt Belisle have the lowest ERAs of the bullpen regulars at 1.94 and 1.98, respectively. With lefty Solis as a situational option, they are most likely to pitch the seventh.

Oliver Perez remains Baker's fireman, the guy who can get them out of a jam. Only five of 36 runners he has inherited have scored this season.

Yusmeiro Petit is the long man and the go-to guy in extra innings. The success of the starters means he hasn't gotten much work this season, but Baker has seemed reluctant to use him in late-inning situations unless it's has been an emergency. Just 14 of his 48 innings this season have come in late/close situations.

A closer with the credentials Melancon brings to the Nats can only improve their chances of winning games in the regular season and beyond. If Baker manages his other relievers well the rest of the way, this could still be a special season.

Marty Niland blogs about the Nationals for D.C. Baseball History. Follow him on Twitter: @martyball98. His thoughts on the Nationals will appear here as part of MASNsports.com's season-long initiative of welcoming guest bloggers to our site. All opinions expressed are those of the guest bloggers, who are not employed by MASNsports.com but are just as passionate about their baseball as our roster of writers.