After a rough 2 1/2-week stretch, the Washington Nationals have picked up the pace thanks in part to a dominant bullpen.
The Chicago Cubs, meanwhile, can't seem to solve their late-inning woes.
The Nationals try to extend their season-high winning streak to five when they open a three-game set against the visiting Cubs on Friday night.
After dropping 12 of 18 from April 12-30, Washington (19-15) has gone 6-1 this month following a two-game sweep of Detroit.
Relievers Ryan Mattheus, Drew Storen and Rafael Soriano combined for three scoreless innings during Thursday's 5-4 victory.
The Nationals' bullpen has been superb in May, throwing 15 shutout innings while allowing just 12 baserunners and striking out 11. Soriano, among the major league leaders with 12 saves, hasn't allowed a run in his last 12 innings, and Craig Stammen has thrown 9 2-3 straight scoreless innings with 11 strikeouts.
The Cubs (13-21), in contrast, saw their relief corps let another win slip away Wednesday, allowing two runs over the last three innings of a 5-4 loss to St. Louis.
"We just can't seem to shut anybody down in the sixth, seventh inning," manager Dale Sveum said. "We're getting two strikes on people, we just can't make a pitch when we have to."
Sveum's bullpen has a 6.75 ERA over the past nine games, giving up 25 hits and 17 walks while hitting five batters in 22 2-3 innings.
The Cubs, losers in five of seven overall, dropped to 5-8 in one-run games.
"It kind of speaks well for our team," reliever James Russell told MLB's official website. "We don't give up, and we're always in the game. If breaks fall our way, then we win a lot more games than we have right now."
That poor relief cost Jeff Samardzija (1-4, 3.09 ERA) a win Saturday. The right-hander surrendered four hits over six innings and left with a 4-2 lead before Carlos Marmol and Hector Rondon allowed four runs in the eighth during a 6-4 loss to Cincinnati.
Since winning on opening day, Samardzija has gone 0-4 over six outings while receiving 12 runs of support. He went 1-1 with a 1.15 ERA over two starts versus Washington last season, striking out 16 over 15 2-3 innings.
Samardzija must face a resurgent Adam LaRoche, 9 for 17 while hitting safely in six straight games. LaRoche, who was batting .129 before that streak, recorded his 10th RBI on Wednesday after leading the team with 100 last year.
"I like where he's at," manager Davey Johnson said before Wednesday's game. "I think he's seeing the ball better. His timing's coming around."
The same might be said of Alfonso Soriano, who hit .367 during Chicago's recently completed 10-game homestand. However, he's in a 1-for-16 slump on the road, where the Cubs have a major league-worst .207 average - including .140 with runners in scoring position.
Soriano, who hit a career-high 46 home runs and stole 41 bases in his only season with the Nationals in 2006, has hit .214 in his last eight games at Washington as the Cubs have gone 1-7.
The Nationals give the ball to Ross Detwiler (1-3, 2.50), who has a 4.50 ERA in losing a career worst-tying three consecutive starts. The left-hander has received one run of support during that skid, which includes a 3-1 defeat at Pittsburgh last Friday as he allowed three runs on a pair of homers in five-plus innings.
"I've seen him sharper," Johnson said. "He had trouble getting the ball down."
Scott Hairston is 5 for 9 with a homer and three doubles off Detwiler. Darwin Barney and Anthony Rizzo, though, are a combined 0 for 8.
Rizzo had his second three-hit effort in three games Wednesday and is batting .429 over his last 13.