NEW YORK -- Once the stable backbone of what had looked like a World Series contender, the New York Yankees' bullpen lately has shown a measure of the inconsistency and uncertainty that has defined the overall team's recent mediocrity.

It's all been puzzling and perplexing for a team and a bullpen that had been a serious roll much of the season.

Poor results from reliever Dellin Betances caused the Yankees to blow a one-run lead in Sunday's eighth inning. That blown lead left the Yankees, who have spent much of September in must-win mode, with a 3-2 loss to the Toronto Blue Jays.

"I'll take the blame on this one," Betances said.

With some bullpen help possibly on the way this week with closer Aroldis Chapman potentially returning from injury, perhaps the days of relievers taking blame for blown saves will soon be over. Maybe brighter days, ones in which they share the credit in wins, are back on the way.

Despite this loss, there was some good news Sunday for the Bronx Bombers. The Oakland Athletics, the team the Yankees are trying to hold off in the wild-card standings, also lost. New York's lead over Oakland for the top wild-card spot entering an off day Monday remains at 1 1/2 games.

Still, the Yankees -- losers of 11 of their past 19 games -- know that's not good enough with the rival Boston Red Sox coming to town Tuesday.

"We've got to play better -- clearly," manager Aaron Boone said. "We're not playing our best right now, but the history of this game is littered with stories of teams that went into the playoffs in different scenarios: limping, playing great.

"The bottom line is you've got to be playing right when it counts."

Since the All-Star break, the Yankees' bullpen has taken a step back from its first-half performance.

Across much of the first half, the group was automatic. With an offense that also frequently delivered late in games, collecting timely hits and walk-off home runs, the Yankees seemingly always felt as if victory was at hand, even if they gave the bullpen the ball without a lead.

Yankees reliever Dellin Betances has taken the loss in three of his last seven outings. AP Photo/Adam Hunger

Back then, Yankees relievers sported a 2.69 collective ERA. Betances, who has mostly dominated out of the bullpen this season, had a 17 2/3-inning scoreless stretch in which he allowed only three hits and had 30 strikeouts.

Similarly, right-hander Chad Green had a 17 1/3-inning scoreless stretch from late May through early July, and Jonathan Holder didn't allow a run across 23 appearances in late April to late June.

Lately, only one Yankees high-leverage reliever has had a similarly impressive run. Green has allowed just one run in his last 15 1/3 innings.

In addition to posting a higher ERA (4.23) since the break, Yankees relievers also have allowed more walks and home runs per nine innings and have fewer strikeouts per nine innings in the second half.

"Obviously, you don't want to give up the lead," Betances said. "It doesn't matter if it's early in the season or late. It sucks any way."

Betances' lone inning of work Sunday, the eighth, was a veritable nightmare. He allowed a pair of runs and four hits. Only one of the hits was struck with any true pop. Justin Smoak's single to right field had an exit velocity of 92.4 mph, according to Statcast. Two batters later, Randal Grichuk flared a base hit with a 65.1 mph exit velocity that resulted in an RBI double that plated the go-ahead run.

"Dellin threw the ball fine," Boone said. "It was just one of those days where placement's everything. Tough result, but no issue with how he threw the ball."

Whether Betances threw the ball well or not isn't the issue. The issue is the "result" portion of that comment.

This time of year, the result is what really matters.

For the third time in seven outings, Betances received a loss. He got one last Sunday at Seattle when the Mariners manufactured another eighth-inning go-ahead score. Four outings before that, Betances gave up a pair of ninth-inning home runs to the Tigers, who stole another game from the Yankees in the Bronx.

Those showings from Betances came after he had a hand in wins in his previous nine appearances.

"We're getting pushed around a little bit right now because it's difficult and we're not quite our best, [but] this thing ain't even close to done," Boone said of his team's positioning in the playoff picture. "We're trying to right this ship and get clicking, get certain guys going, jump-started. A couple guys potentially back in the fold very soon will help. But we've got to get jump-started."

One of the players the Yankees should have back at some point this week is Chapman, the closer whose balky left knee finally forced him to the disabled list last month.

The Yankees are hoping the time off will not only ease the tendinitis issue Chapman had been playing through, but that it also will help the Yankees reset a bullpen that has spent nearly the past month working a revolving door of pitchers in the closer's role.

With a true and committed pitcher in the back end of the bullpen, others, including Betances, can return to the set-up roles that helped make the entire group click earlier in the season.

The good news for the Yankees' bullpen is that, like the rest of the team, it still has time to get back to what made it so successful. Consider the following from the ever optimistic Aaron Judge, the other key player the Yankees should get back fully from injury later this week.

"We've still got plenty of baseball left to get hot," Judge said. "It's all about what team is hot at the end. If we can get hot these last two weeks, take that into the playoffs, we're going to be in a good position."