If the Washington Nationals acquire relief help, who gets the ax?

The Washington Nationals have been one of the most exciting teams in baseball this season, rising from the grave on May 24 to climb out of the NL East basement and cement themselves as playoff contender ahead of the July 31 trade deadline.

But the team’s Achilles heel has remained its relief corps all season. Washington’s 6.02 bullpen ERA is the highest mark in the majors this season and ranks behind only the 2007 Tampa Bay Rays (6.16) for the second-worst reliever ERA since 1953.

With the trade deadline just two days away, the Nationals’ front office is tasked with acquiring reinforcements that will beef up a roster that’s otherwise stacked from top to bottom. And yet, although there’s a clear need for some bullpen help, there’s no clear answer as to who will be cut, demoted or traded to make room on the depth chart.

Aside from closer Sean Doolittle (2.72 ERA, 23 saves), there are few locks to stay in Washington past July 31. It’d be surprising to see the Nats cut ties with Fernando Rodney, who’s been solid since being released by the Oakland A’s in late May, or Wander Suero, the 27-year-old righty who’s battled inconsistency but has come up big in some late-inning situations this season.

According to Roster Resource, the only relievers in Washington with minor-league options are Tanner Rainey and Suero. Rainey’s start to his season was strong, compiling a 1.59 ERA over his first 12 appearances; he then struggled through the second half of June before going on a nice run in July. Although he’s probably been the Nats’ third- or fourth-best reliever this season, Rainey could be optioned to AAA-Fresno until September to maintain roster flexibility.

Given the Nats are expected to acquire at least two relievers to solidify the back end of their ’pen, the front office will still have to cut at least one other pitcher even if it does option Rainey. Tony Sipp, Matt Grace, Javy Guerra and Michael Blazek are fighting to make their cases for a roster spot, with none standing out from the pack.

Multiple reports have indicated Washington is interested in acquiring a southpaw set-up man, which means the team will likely be cutting at least one of its lefties. Doolittle isn’t going anywhere, so either Grace or Sipp will likely get the pink slip. Sipp is owed the remainder of his one-year, $1.25 million deal that includes a mutual option for next season, while Grace is still signed to his rookie deal and under contract through 2022.

Grace is perhaps the more interesting of the two. The 30-year-old left-hander doesn’t strike out very many hitters and has an ugly 5.93 ERA in 41 innings this season, posting the second-worst soft-hit rate among NL relievers (11.3%). However, he thrived as the team’s first-ever opener Saturday and has been effective against left-handed hitters this season. In fact, Doolittle is the only Nats reliever with a lower opponents’ OPS against lefties (.618) than Grace (.659).

The Nats don’t like to eat money unnecessarily but cutting Sipp has fewer long-term ramifications. The journeyman reliever was outstanding for the Houston Astros last season (1.86 ERA in 38.2 innings) but is on pace to finish with an ERA above 4.00 for the third time in the last four years. At 35 years old, Sipp doesn’t offer a ton of upside for helping the Nats make a pennant run.

Of course, Washington could opt to retain both lefties and keep Rainey in the majors, making Guerra and Blazek the most logical cuts. Blazek has just two appearances this season after spending the last two years in the minors, so he’s easily the most expendable reliever on the team. Guerra has been average for a middle-innings reliever but is actually pitching worse for Washington than he did for the Toronto Blue Jays before he was claimed off waivers.

The team also has 40-man relievers Kyle Barraclough, James Bourque and Kyle McGowin in the minors and Jonny Venters, Justin Miller, Koda Glover and Austen Williams on the Injured List. Midseason signee Brad Boxberger has done well for AA-Harrisburg. Spot starters Erick Fedde and Austin Voth (10-Day IL) could also be options for the bullpen come playoff time.

The only thing for certain is that more names will be added to this mix by the end of the week. Barring something completely unexpected, the Nationals will be active on the reliever market — likely acquiring two or three new arms. It’s going to be equally intriguing to see who they decide to let go as a result.