Before the season began, the Nationals knew they had a void at the back end of their bullpen. And virtually every day once the season began Washington's late-inning concerns were heightened.
They had a strong enough rotation and lineup to still be the best team in the National League East, but for a franchise that began as the Montreal Expos in 1969 and had never appeared in a World Series, the focus was more about making that big step onto baseball's ultimate stage.
And in the two weeks leading up to the July 31 non-waiver Trade Deadline, the Nationals answered their bullpen questions, putting the team into position to fill the World Series hopes that came with the franchise when it moved to Washington, D.C., prior to the 2005 season.
The Nationals, however, aren't the only team that swung pre-Deadline deals to enhance their championship hopes. Each of the eight teams still playing this postseason was active up to the Deadline, with the four NL clubs having made the additions with the biggest impact.
The Nationals, who had a bullpen that ranked at the bottom of the NL with a 5.27 ERA and had converted just 22 of 36 save opportunities prior to the arrival of current closer Sean Doolittle and reliever Ryan Madson from the A's on July 17, have been the best in NL since with a 3.36 ERA and 24 saves in 27 opportunities. Doolittle has assumed the role of closer, with Madson and July 31 trade acquisition Brandon Kintzler providing the setup work.

The Dodgers have fallen short of the Fall Classic in their past 10 postseason opportunities since they last won a World Series in 1988, including being knocked off in the NL Championship Series twice and NL Division Series twice in the past four years. That's why they not only dealt three prospects to the Rangers for starting pitcher Yu Darvish, but also added relievers Tony Cingrani from the Reds and Tony Watson from the Pirates. Darvish got the attention with his addition, but Cingrani (2.79 ERA after the deal) and Watson (2.70 ERA after the deal) have combined with Brandon Morrow to ease the pressure in getting games to closer Kenley Jansen (41 of 42 in saves with a 1.32 ERA).
The D-backs were one of the better offensive teams to begin with, but with the July 18 addition of J.D. Martinez from the Tigers they are even better. He hit .302, but more importantly, in 62 games after his arrival, Martinez hit 29 home runs and drove in 65 runs, both of which ranked third on the D-backs for the entire season, behind only Paul Goldschmidt (36 HR, 120 RBIs) and Jake Lamb (30 HR, 105 RBIs).

The Cubs were concerned enough about their rotation that they dealt with the crosstown White Sox, giving up four prospects for lefty Jose Quintana, who not only went 7-3 after the July 13 deal, but who seemed to help rejuvenate veterans Jonathan Lester and John Lackey. Lester was 5-6 at the time of Quintana's arrival but won eight of his final 10 decisions, and Lackey went from 5-9 before the deal, to 7-3 after the acquisition of Quintana.
The Red Sox made their intentions known during the offseason with the acquisition of Chris Sale for the rotation last December for a package that included baseball's most talked-about prospect, Yoan Moncada. Boston then spent July adding bullpen depth with the acquisition of Addison Reed from the Mets, and found offensive help with the addition of infielder Eduardo Nunez from the Giants, who hit .321 with eight home runs and 27 RBIs in 38 games after the deal. But Nunez will miss the rest of the ALDS, as well as the AL Championship Series, after reaggravating his right knee in Game 1 on Thursday.
The Yankees were able to address setup needs in the bullpen with the acquisition of relievers Player Page for David Robertson and Tommy Kahnle, who came from the White Sox along with third baseman Todd Frazier, but they didn't get what they hoped for from Frazier or starting pitchers Jaime Garcia and Sonny Gray in their bid to overtake the Red Sox for the AL East title. Kahnle (2.70 ERA after the deal) and Robertson (1.03 ERA after the deal) combined to make 62 appearances. Gray and Garcia were a combined 8-11 with a 4.84 ERA in 19 starts, and Gray failed to get through the fifth inning as the Cleveland topped New York, 4-0, in Game 1 of the AL Division Series on Thursday night. Frazier hit .222 in 66 regular-season games with 11 home runs and 32 RBIs after the trade.

The Indians added to their bullpen by acquiring situational right-hander Joe Smith from the Blue Jays, who worked 18 1/3 innings over 21 appearances in the final two months of the season. The Tribe also acquired Jay Bruce from the Mets in an August trade which came after the Yankees reportedly tried to swing a deal with their crosstown rivals for the veteran slugger. Bruce went on to hit .248 with 28 RBIs and seven homers in 43 games for Cleveland after the deal, and he went 2-for-3 with a two-run homer and three RBIs in Thursday's ALDS win over the Yanks.
The Astros didn't shake things up at the July 31 Deadline, but they made a bold move on Aug. 31, giving up three prime prospects for Justin Verlander after putting in a waiver claim that the Tigers accepted. Verlander gave Houston a dominate top-of-the-rotation starter, and he held the Red Sox in check to earn a win in the Astros' 8-2 Game 1 victory in the ALDS on Thursday. Prior to July 31, Houston added veteran Francisco Liriano in a deal with the Blue Jays. The Astros moved him from the role of a starter to a left-handed bullpen specialist, limiting Liriano to an inning or fewer in 19 of his 20 appearances after the deal.