The Boston Red Sox will turn to Roenis Elias to fill the void at the back end of their rotation, at least for now.

The question that Boston Red Sox fans have been wondering for weeks has finally been answered – we now know who the fifth starter in the rotation is going to be.

The team announced that Roenis Elias will start against the Seattle Mariners on Friday, with Rick Porcello‘s start getting pushed back a day. David Price will close out the series at Fenway on Sunday on regular rest.

The back of the rotation has remained a question mark in recent weeks in the wake of Clay Buchholz being banished to the bullpen and Joe Kelly getting shipped to Pawtucket. A fortuitous schedule has allowed the Red Sox to push forward with a four-man rotation, but eventually they would need to decide on a fifth starter.

The Red Sox have been looking for someone to step up and claim the opportunity over the past couple of weeks, with their options essentially boiling down to four candidates.

Kelly seemed to be the least likely choice, given the brutal 8.46 ERA that he owns through 6 starts at the big league level this season. If that wasn’t enough, Kelly left his most recent start last week with a groin injury and has yet to return to the mound, essentially ending his chances of rejoining the Red Sox rotation this weekend.

The chances of Henry Owens getting recalled were lukewarm at best. His brief stint in the majors this season was also unsuccessful and his control troubles have continued to haunt him since his return to Pawtucket.

That left the choices coming down to Buchholz or Elias, so pick your poison. Farrell explained that the decision was influenced by the matchup, as the left-handed Elias could stymie the lefty bats in the Mariners lineup. For his career, Elias has limited opposing left-handed batters to a .224 average and .655 OPS.

Seattle is hitting a modest .267 against right-handed pitching this year, but with a .788 OPS that ranks third in the league. Compare that to the .732 OPS that the Mariners own against lefties and it’s clear why Elias is getting the start against Seattle’s lefty-heavy lineup.

It also doesn’t hurt that the Red Sox acquired Elias from Seattle, so he’s familiar with the hitters in their lineup, despite spending the entire current season in the minors.

Elias has found modest success in Pawtucket, posting a 4-3 record with a 3.54 ERA. He has come on strong lately, allowing two runs or less in four of his last five starts. His last two starts have included a complete game effort where he allowed only one run, which was followed by seven shutout innings on June 10.

Will Elias’ stay in the rotation stick or is it only temporary? That will depend heavily on how he performs on Friday, but Farrell could always look at the matchup again before picking his starter the next time this spot comes up in the rotation.

Ideally, the fifth starter is merely a placeholder until the Red Sox can swing a deal to bring in another pitcher that would fit near the top of the rotation. Dave Dombrowski is surely scouring the trade market for any available options and won’t be shy about pulling the trigger if anything appealing is brought to his desk.

All the Red Sox need to do is find a fifth starter to get them through at least a few more weeks until a trade can be completed prior to next month’s deadline. At least for the moment, that responsibility has fallen on Elias.