CLEVELAND -- If the past two weeks have proven anything, it’s that the San Francisco Giants can be a dangerous team.

But, as of right now, they’re not a complete team, either.

While the Giants’ 8-5 showing over the last two weeks has helped move them back into the National League postseason picture, Sunday’s 5-4 loss to the Guardians was a prime example of how threatening San Francisco’s roster can be -- while also shining a spotlight on its deficiencies.

They got a solid start from Hayden Birdsong and another big hit from Michael Conforto (a Statcast-projected 440-foot two-run home run), but San Francisco's taxed bullpen ended up coughing up the lead when Sean Hjelle allowed a back-breaking, pinch-hit go-ahead three-run home run to Bo Naylor in the sixth inning.

"I made a [bad] pitch, and he put a good swing on it,” Hjelle said. “That's it. Plain and simple. I need to make a better pitch in that situation."

An inning earlier, Hjelle saved the Giants' lead by striking out José Ramírez with the tying and go-ahead runs on base. That changed in the sixth inning when he left a sinker over the plate that Naylor mashed to right field.

After the ball made contact with Naylor’s bat, Hjelle briefly watched it fly towards the right-field bleachers before he put his hands on his hips and stared at the grass by Progressive Field’s pitching mound.

Hjelle opened the sixth by retiring the first two batters, but the inning was extended when Andrés Giménez reached base on a single that glanced off shortstop Nick Ahmed’s glove. That was followed up by a fluky infield single from Tyler Freeman, which set up Naylor’s heroics.

“I’ll take my chances with Hjelle,” Giants manager Bob Melvin said. “He [allowed] a bloop hit and then a ground ball. It happens sometimes.”

A day after former top prospect Kyle Harrison made his return from the injured list, Birdsong -- the team’s No. 4 prospect -- allowed two runs in 4 2/3 innings.

“I felt really good at the beginning,” Birdsong said. “I was making my pitches, and hitting my spots. I was hoping I’d just keep doing that, but I fell behind a bit in the fourth.”

He only allowed one baserunner in the first three innings before the Guardians tagged him for two runs on four straight hits to start the fourth inning.

“Those guys are good hitters; that’s a good team,” Birdsong said. “Things happen, those guys can hit. I was happy I was able to work out of it, and we were able to keep the lead.”

The main reason he got out of the fourth inning was because of an incredible play from Matt Chapman to cut down the potential tying run at home.

The two-time Platinum Glove winner corralled a ground ball from Freeman and let loose a 73.4 mph seed to Patrick Bailey, who slapped a tag on Josh Naylor moments before he touched home plate.

The Guardians challenged the play to see if Bailey had blocked the plate, but the rule wasn’t enforceable since it was a ball on the infield.

“You don’t have time to position yourself; you just kind of go where the ball takes you when it’s on the infield,” said Melvin, a former catcher himself.

Three pitches later, Birdsong picked Freeman off at first to end the inning.

While the Giants went 3-3 on the road trip, and have won three of their last four series, they’re leaving Cleveland frustrated after dropping two straight games that they had opportunities to win.

“We were in every game on this trip,” Melvin said. “I just would have liked to have been one game better.”

The Giants will take a big step toward looking like a more complete team on Tuesday when Blake Snell returns from a month-long stint on the injured list. While the reigning National League Cy Young winner hasn’t pitched like an ace this year (9.51 ERA in 23 2/3 innings), his presence on the mound will be a boon for a Giants bullpen that’s had to cover an MLB-high 141 1/3 innings since he was placed on the injured list on June 3.

Snell’s start will kick off a six-game homestand that could end up determining the trajectory of the Giants' season.

“Our bullpen has continued to step up, and we’re excited to get Blake back in there and some guys who can go deeper in games to take some pressure off our bullpen,” Melvin said.