One of the most interesting trends of the offseason has been the investment analytical teams like the Athletics and Rays have made in their bullpens. With the Rays, specifically, a pair of trades and a free agent signing have added two relievers with experience closing games to a bullpen that already boasted more than 100 career saves. Together, they should form one the most dominant bullpens in all of baseball with several attractive options for deeper fantasy leagues.

The Rays landed a likely bargain in Grant Balfour for two years and $12 million thanks to his failed physical with the Orioles. It is difficult to be overly concerned with his health status given that Orioles seem to have had more failed physicals than actual signings this offseason. The real reason owners should be pessimistic of Balfour is the handful of excellent arms behind him that boast numbers as good as he has in their careers, if for fewer seasons. In fact, Balfour is one of four Rays relievers to have struck out at least a batter per inning in his career.

That is not to say that Balfour is not worth drafting, because he is. He has been amazingly consistent with an ERA of 2.59 or better in four consecutive seasons. While his walk rate has crept up to near four batters per nine, his strikeout rate has increased in step. And his exceptional 7.9 percent home run per fly ball rate should not be threatened by the move to Tropicana Field (96 HR index in 2013), which has been nearly as pitcher-friendly as O.co Coliseum (92 HR index in 2013) in Oakland in preventing home runs. Most importantly, Balfour has no platoon splits. Opposing left-handers have a .272 career wOBA while opposing right-handers have a .281 wOBA against him. Balfour is a safe bet to perform up to his usual standard this season, and if he does, he will remain the closer. As such, he belongs in the mid-teens among relievers in typical formats.

The other two new additions are Heath Bell—who the Rays acquired with Ryan Hanigan in a three-team deal with the Reds and Diamondbacks—and Brad Boxberger—who the Rays acquired with Logan Forsythe from the Padres. After a tremendous three-year run as the Padres closer, Bell has struggled the last two seasons with ERAs of 5.09 and 4.11. However, a closer look at his 2013 season shows that most of that struggle was the result of an anomalous 18.5 percent home run to fly ball rate. His 3.08 xFIP was in line with his elite seasons in San Diego, and where Balfour can expect a bit less help from his new park, Bell should be treated much kinder by the Trop than he was by Chase Field (103 HR index in 2013). Bell may not be second in line for saves, but I expect a vintage season from him statistically.

Brad Boxberger will start the season buried even further down than Heath Bell, in all likelihood, but in formats like Ottoneu and AL-only dynasty leagues, he has my interest piqued. He is not a tremendously hard thrower, but he features a three-pitch repertoire that has generated an 11.7 percent swinging strike rate since 2012, similar to Joe Nathan, Jonathan Papelbon, and Edward Mujica. The walks are a serious issue; he has walked more than five batters per nine in each of his two seasons. However, Boxberger showed better control in recent stints in the minors, and with just 49.2 big league innings, it is too soon to write him off as having prohibitively poor command.

Joel Peralta looked like the in-house candidate to close before the Rays added Balfour. He has his own streak of four consecutive seasons of a 3.63 ERA or better. Also like Balfour, Peralta has no platoon splits, allowing a .303 wOBA to left-handed hitters and a .295 wOBA to right-handers in his career. The Rays have three consecutive team options for the 36-year-old Peralta after this season, so they can increase the leverage of his role with financial impunity. The uncertainty of the pecking order between Bell and Peralta makes it difficult to draft either among the first handful of non-closers in non-holds leagues, but like Bell, I would expect Peralta to be successful if given the opportunity.

Jake McGee has two characteristics that prevent him from being on even footing with Bell and Peralta. The first is team control. A move to the closer role would increase his arbitration salaries over the next few years, which the Rays can easily avoid with their other reliever options. The second is his left-handedness. McGee is far from a LOOGY; he actually leads the bullpen with 10.8 strikeouts per nine over his career and has a reverse platoon split (.279 wOBA versus LHB and .253 wOBA versus RHB). The issue is that the only other left-hander in the Rays pen is Cesar Ramos, who beyond being the clear worst reliever (and fantasy non-entity) on the roster is primarily the long man, in any case. McGee could handle ninth inning work, but the Rays are better off letting opposing lineups dictate his usage.

The final fantasy-relevant Rays reliever is Juan Carlos Oviedo, the former closer formerly known as Leo Nuñez. It has been three years since he last recorded a save on the Marlins; four since he was last solid statistically in that role. Visa issues have delayed his reporting to spring training with the club, which might be more an issue for Oviedo than most because of his inability to pitch in 2013 because of Tommy John surgery. With 92 career saves and still short of his 32nd birthday, Oviedo merits a bit of attention. But without having seen him pitch in a few years, he is the last of the Rays relievers worth considering and is likely undraftable in all formats.