MLB's best bullpens after the winter meetings

The importance general managers place on building a strong bullpen continues to grow.

Teams have showcased a willingness to sacrifice big dollars and top prospects at an unprecedented rate this offseason in order to land an established arm that will help solidify the back end of their bullpen.

Coming off the winter meetings, the top four free-agent relievers have signed for a combined $97 million, while the Boston Red Sox, and most recently, the Houston Astros have packaged away nine total prospects in order to land Craig Kimbrel, and Ken Giles respectively.

Here are the top bullpens heading into 2016 following a flurry of winter moves:

Boston Red Sox

Scrutinized for his inability to build a bullpen in Detroit, new Red Sox president Dave Dombrowski is having no such problems in Beantown. In a few short months, he turned one of the worst relief corps from a season ago into one of the best. The Red Sox plan to sandwich Koji Uehara in between new additions Carson Smith and Kimbrel. The trio is arguably one of the best in the majors, having struck out 411 in 304 innings over the past two seasons. Smith cost the Red Sox an innings-eating starter in Wade Miley, but gives them a strong complement to Uehara and Kimbrel.

Houston Astros

Two years removed from having MLB's worst bullpen, the Astros have turned their biggest weakness into arguably their greatest strength. General manager Jeff Luhnow landed both Luke Gregerson and Pat Neshek last winter, and bolstered that core by re-signing Tony Sipp and trading for Giles on Saturday. Luhnow wanted to add a hard-throwing piece at the back of the pen, and he certainly has that in the 24-year-old, who averages 97 mph on his fastball, and has struck out 151 over 115 2/3 career innings. The cost to land a top-tier closer was far from cheap, as Houston packaged 2013 first overall pick Mark Appel and four other arms in exchange for Giles.

Kansas City Royals

The Kansas City Royals wasted little time replacing Greg Holland, signing veteran right-hander Joakim Soria to a three-year deal Thursday. The addition of Soria strengthens a Royals bullpen that already features the almost unhittable Wade Davis as well as the hard-throwing duo of Kelvin Herrera and Luke Hochevar. Davis has allowed just 23 extra-base hits, including only three home runs, over the past two seasons - a span of 164 1/3 innings. Soria converted 24 saves last season, and gives the team that's set the bar for what makes a strong bullpen another quality arm.

New York Yankees

Andrew Miller and Dellin Betances account for two of just three relievers who eclipsed the century mark in strikeouts last season. The duo helped push the New York Yankees to a wild-card berth, going 73-2 when entering the eighth inning with a lead. The pair struck out 231 over 145 2/3 innings and limited opponents to a minuscule .154 average in 505 at-bats. The Yankees have yet to add to their pen this offseason, but boast a young homegrown core of Chasen Shreve, Nick Rumbelow, and Branden Pinder.

Pittsburgh Pirates

The Pittsburgh Pirates' bullpen doesn't possess the flamethrowers like its counterparts, but that hasn't stunted its effectiveness. Led by closer Mark Melancon, who converted a franchise-record 51 saves last season, Pittburgh's bullpen posted a major-league best 2.57 ERA. Setup man Tony Watson and Melancon owned a sparkling 0.94 WHIP over 152 innings in 2015, and the Pirates were 79-1 when leading after the seventh inning. The Pirates added veteran reliever Juan Nicasio on Thursday to complement a strong core. He struck out 65, while allowing one homer in 58 1/3 innings last year.