CLEVELAND -- The Guardians are out in front because of what they do in the back. Arguably more than any element of this club, it is the bullpen, anchored by Emmanuel Clase and the Rookies Three (Cade Smith, Hunter Gaddis and Tim Herrin), that has created the confidence it takes to make a big run up the division standings.

But after the Guards suffered a series and doubleheader sweep at the hands of the surging Arizona Diamondbacks this week, it has become difficult to deny the bullpen is bending in ways it has not all year. And that makes it all the more imperative that the experiment the front office embraced with the in-season acquisitions of Alex Cobb and Matthew Boyd -- two veteran rotation arms coming off injury -- pays off.

With losses of 7-3 and then 5-3 in Wednesday’s twin bill at Progressive Field, the Guards have dropped five straight for the first time all year (even four straight after the opener was a first for them in 2024).

“Our guys,” said manager Stephen Vogt, “are grinding through it.”

They’ll have to continue to do so. Counting Wednesday’s action, Cleveland is in a 22-games-in-22-days stretch that includes three doubleheaders, including Friday at Minnesota after Thursday’s off-day.

So the bullpen will continue to be leaned upon heavily. And when leaned upon heavily of late, there have been late-inning letdowns.

Against the Orioles on Saturday, it was 3-2 Baltimore going into the eighth, when the O’s erupted against Xzavion Curry for four runs to put it away.

On Sunday, a Josh Naylor homer in the fifth cut the Guards’ 6-2 deficit down to 6-5. But Herrin and Nick Sandlin were ineffective in the O’s two-run sixth.

Then Monday, in the opener of this set with the Snakes, starter Logan Allen left with a 3-2 lead, but Smith coughed up the lead in a two-run sixth. When it was 5-4 Guards entering the eighth, Scott Barlow allowed a two-run homer to Joc Pederson.

In Wednesday’s doubleheader, it was a now-too-familiar pattern -- the starter departing early, the offense fighting to keep it close, the bullpen letting the opponent put it away.

Ben Lively allowed four runs in five innings in Game 1. But the Guards’ deficit was manageable until it wasn’t. It was 4-2 entering the late innings. Eugenio Suárez ripped a run-scoring double off Pedro Avila in the eighth, a red-hot Ketel Marte took newly promoted Anthony Gose deep with a two-run shot in the ninth, and that was that in a 7-3 loss.

Game 2, same deal. The veteran Carlos Carrasco, whose rotation spot (and perhaps roster spot) is in jeopardy with the pending arrivals of Cobb and Boyd, gave up four runs in 4 1/3. In the sixth, José Ramírez hit his 30th homer of the season to cut the deficit to 4-3. But Sandlin was taken deep by Randal Grichuk with a solo shot in the seventh, and the Guards did not recover.

Toss in an iffy ending to last Friday’s win over the Orioles, when Barlow allowed three in the seventh, and the bullpen’s ERA over the last six games is 5.71.

For a rookie skipper, especially, Vogt has done a masterful job of in-game management with his ‘pen this season. And the Guards have been ultra-careful with pitch counts and rest days and warmups and all the things baked into the big league calendar that can wreck a reliever.

“We know we've used them a lot,” said Vogt, “but they're also some of our best pitchers. And these guys work really hard to stay healthy. Our medical staff and strength and conditioning staff are tremendous in keeping these guys strong and fit.”

But no number of optionable arms or safeguarding strategy can overcome the fact that the Cleveland rotation has delivered the fifth-fewest innings of any starting set in MLB this season. It has led to the Guards being the only team with more than three relievers having made 50 appearances this season. In fact, they have five – Gaddis (56), Barlow (53), Clase (53), Herrin (53), Smith (53). The next time Sandlin (49) takes the mound, he’ll join the list.

Cleveland’s front office did not add to the ‘pen during a Trade Deadline in which relievers were flying left and right. And it took a calculated gamble on Cobb, who will make his Guards debut in the second game of Friday’s doubleheader with the Twins, and Boyd, who was terrific in what is expected to be his final rehab start after Tommy John on Wednesday, delivering meaningful innings down the stretch.

The Guards sorely need such innings. Because the bullpen has taken on a lot of them, to date. And for the first time all season, it is showing cracks.