Teams with an average to decent starting rotation don't really have a need for more than, say, one long reliever. The Orioles, though, have a bad rotation and currently have several swingmen on the roster: Dylan Bundy, Ubaldo Jimenez, Vance Worley, Odrisamer Despaigne, and Tyler Wilson. Yes, Bundy is slated in the rotation right now and is firmly in the team's long-term starter plans, but he was used as a multiple-inning reliever earlier in the year and it's at least possible he shifts back to that role before the end of the season.
Jimenez is in the swingman role for two reasons: 1) He's been terrible and lost his regular starting gig; and 2) He's only still on the team because the Orioles still haven't figured out a convenient way to unload his contract (which they've been trying to do since late 2014).
Besides Bundy, the real hero of the long relief corps is Worley. In 62.1 innings out of the bullpen and in four starts, he's posted a 2.89 ERA and has been getting a bunch of ground balls (48%). His peripheral numbers aren't as good, with a FIP near 4, but that's hardly awful. And considering the O's plucked him from waivers and are paying him $2.6 million this season, those are decent, and much-needed, results.
Despaigne has a strikeout rate under six and a walk rate of nearly five, but somehow he's managed to pitch 24 innings without being a complete disaster. And Wilson has had his ups and downs, but in limited duty has been more effective out of the bullpen - when he's not asked to work through a lineup more than once or twice.
This is far from a perfect situation, and it's something the Orioles have been dealing with all season. Ideally, the O's would employ starters capable of pitching six innings and then handing the ball off to Mychal Givens, Darren O'Day, Brad Brach, and Zach Britton. Surely that's what Dan Duquette hoped for when bringing aboard Jimenez in 2013 and Gallardo this past offseason. And obviously, that's not the case this season. O's starters have thrown the third fewest innings in the majors. Enter the team's collection of long relievers.
It's unclear exactly how the addition of Wade Miley will change things. Most likely, he'll be slotted into the rotation with Chris Tillman, Kevin Gausman, Yovani Gallardo, and Bundy (for now). The Orioles need to create a spot on both the 25- and 40-man rosters, and the O's have also been working with a three-man bench lately. Wilson and Despaigne are the two long relievers who have options, so likely one of them will be sent down. You'd have to think the O's would prefer to jettison Jimenez from the roster, but that appears unlikely.
Buck Showalter will need to keep going to this cast of characters, and unfortunately, this could be the case next year as well. The only real hope is that this version of Tillman is for real (a dangerous assumption), and that Gausman and Bundy both stay healthy and continue to progress. Gallardo is somehow getting a pass that Jimenez never received, and Miley is the very embodiment of a back-end starter. If the Orioles don't develop a starter or pull another Miguel Gonzalez out of their hat, there really isn't much relief in sight. It's not like the O's are going to start paying top dollar for starting pitching, which they maybe shouldn't do anyway because of the risks involved.
The Orioles have constructed a flimsy bridge from the rotation to their dominant group of relievers. It's no sure thing this collection of starters can even get the ball to any of their relievers with a lead intact, but these long relievers will play an important part in how the O's fare the rest of the year. It's hard to expect a lot from them, because if they didn't have flaws in their game, they'd be in a starting rotation somewhere instead of a bullpen. But that's more or less what the O's have excelled in these last few successful seasons: getting helpful performances out of unlikely places. They'll need more of that.