There's nothing more comforting to a baseball team than knowing a seventh-inning lead is going to hold up.

And there's nothing more dispiriting than to have a win slip through your fingers because of a leaky bullpen.

The Twins, bearing down on the AL Central title, are about to find out if their bullpen will hold up in the heat of October baseball.

"One of the things someone told me when I took this job is, 'What will drive you crazy sometimes is bullpen construction,' " Twins Chief Baseball Officer Derek Falvey said. "In terms of how you do it year over year and injuries and dealing with some guys going up and down … it's a challenging part of our game."

Bullpens can be volatile. What worked one year can be a disaster the next. Sometimes it can swing from month to month. In the Twins' case, their bullpen has evolved from the hot mess it was into a unit that just might be capable of holding up in the postseason.

Overall, Twins relievers have a 4.22 ERA, which entering Monday ranked 10th-best in the majors. The trouble months were April (4.63 ERA) and July (4.78). Since the end of July, Twins relievers have stepped up their game, posting an 3.88 ERA. In August, their 3.68 ERA was the fourth best in MLB.

Before giving up a home run Saturday in a loss to Kansas City, Taylor Rogers had given up only one earned run over his previous 12 appearances. Now the primary closer, the lefthander has 28 saves, ranking 12th in the majors.

Since Aug. 1, Trevor May has a 1.50 ERA with 32 strikeouts in 24 innings while holding opponents to a .123 batting average.

Tyler Duffey has topped both of them with a 22⅔-inning scoreless string, the longest current streak in baseball. He has 38 strikeouts during the run and has not walked a batter over his past 11⅔ innings.

Even Zack Littell, called up five times this season, has an 0.53 ERA over his past 14 games.

"These guys have been, just frankly, they've been dominant," Twins manager Rocco Baldelli said. "And they've been really good for a long time now. I have no issue saying that. I would anticipate it to continue. Patting people on the back, I don't believe in jinxing anyone. Failing to call it what it is I think would be wrong. They've been excellent."

Plans change

The Twins have come a long way from the start of the season.

Free-agent reliever Blake Parker was brought in to pitch the late innings and share closing duties with Rogers. Ryne Harper made the club as a 30-year-old rookie out of spring training. Adalberto Mejia was supposed to be a lefthanded option. Fernando Romero seemed to be a lock for the bullpen at the start of spring training but was cut from camp. Duffey opened the season at Class AAA Rochester.

Then the Twins had their stumbles out of the gate. In addition to that 4.63 ERA in April, relievers walked 5.04 batters per nine innings, which is dreadful. While Rogers was consistent, others struggled.

The front office was patient until July, when it designated for assignment Mejia, Mike Morin, Matt Magill and Parker over a 12-day span as they decided to give other pitchers a try. Harper, not a high-velocity guy, was used less, struggled and eventually briefly went to the minors.

Meanwhile, Duffey and May continued to work on mechanical adjustments, tinker with pitches and work on different sequencing. Both righthanders have seen their fastball velocity jump. Duffey's average fastball was 90.2 miles per hour when he broke in as a starter in 2015 but has hit 97 on the gun recently. May was a 91.9 mph in 2014, is averaging 95.6 mph this season and has thrown a pitch at 99.8 mph.

But it's not just velocity. Duffey also throws a curveball and will go with whichever pitch is the most effective that game. May is mixing in sliders and changeups more. Both have attacked the strike zone like never before.

"We got tired of hearing everyone say we weren't good when we were," Duffey said. "[Rogers] should have been an All-Star. Guys have come into their roles and have figured some things out."

The right mix?

The Twins addressed the bullpen before the July 31 trade deadline, dealing for veteran relievers Sergio Romo from Miami and Sam Dyson from San Francisco. Dyson has been shut down because of shoulder problems and is looking at surgery and a lengthy recovery. Romo has settled in as the main setup man for Rogers. The savvy 36-year-old righthander doesn't throw hard, but he frisbees a slider toward home plate that vexes hitters.

Baldelli won't address postseason questions until after the team qualifies, but the backbone of the bullpen — with Rogers, Romo, Duffey, May and Littell — is operating at a high level. Cody Stashak, another rookie, has a 1.23 ERA with 10 strikeouts over 7⅓ innings in eight September appearances and figures to be an October option. And 21-year-old Brusdar Graterol, with the 101 mph fastball, is auditioning for a spot in the postseason bullpen. He has his ERA down to 4.32 after striking out the side on Sunday in an inning of work.

This group doesn't even include Randy Dobnak and Devin Smeltzer, who both spent most of the season in the minors but figure to be in the playoff mix as starters, relievers or both.

With the average start in MLB down to 5⅓ innings — and clubs occasionally using relievers as "openers" — assembling a bullpen has never been more important. If the Twins have to go to the bullpen in the sixth inning of a playoff game, they won't have to feel like they are playing reliever roulette.

"You look at all the World Series teams over the last few years and how their bullpens were constructed, they had three or four guys," assistant pitching coach Jeremy Hefner said. "The 2015 Royals team, if the starters went four or five innings, the game was over.

"I don't know if we are quite at that elite level, but these guys are very special and deserve the next two weeks, or three weeks, or four weeks, or however long we play. They deserve the opportunity to showcase themselves."