BOSTON – The starting rotation – backed by a second straight quality start by Tanner Houck – is showing signs of rounding back into form. The offense, a near constant, certainly wasn’t the issue in Wednesday’s gut-wrenching 9-7, 10-inning loss to the Rangers at Fenway Park.

However, there are two issues threatening to prevent the Red Sox from making the playoffs.

And both of them – the bullpen and the defense – helped turn what should have been a sweep into a frustrating, getaway night loss.

“We're still learning. We're still growing as a group,” said Red Sox manager Alex Cora of his defense. “That's not an excuse, because we are better than that. But we’ve got to learn from today and get better.”

The issues in the bullpen, at least at the moment, feel bigger than the defensive lapses that can partly be chalked up to youth.

“We’ve got to keep the ball in the ballpark,” said Cora. “You know, you can talk about sloppiness [on defense], but we’ve got to keep the ball in the ballpark. We haven't done that since the All-Star break. It’s damage with men on base, damage late in the game. We’ve got to figure that out.”

In 24 games since the All-Star break, in which the Sox have a record of 10-14, the bullpen has given up 23 home runs and posted a 6.91 ERA. In nearly every relevant category, Boston’s relief crew is last in MLB since the break.

As they head out for a tough road trip against two top contenders in the Orioles and Astros, the Sox are two games behind the Royals for the third American League Wild Card spot.

In the top of the eighth inning, Trade Deadline acquisition Luis García was struggling again, but he could have gotten out of a jam with the lead still intact if not for rookie shortstop David Hamilton making an error on a grounder off the bat of Leody Taveras.

The Red Sox (63-56) are the first MLB team to win at least 63 of their first 120 games despite making over 85 errors and allowing over 75 unearned runs in those games since the … ‘04 Red Sox.

That team acquired Orlando Cabrera and Doug Mientkiewicz to solidify the defense down the stretch. The current club will need the young players to get sharper as they learn from their mistakes and gain more experience. The potential return of shortstop Trevor Story in September would also be big.

“I mean, we've been talking about this since Spring Training, right?” said Cora. “Defense is going to dictate who we are. And if we don't play defense, we're not going to make it to October. Today, we didn't make a few plays, and it cost us.”

The recent game of push-and-pull the Red Sox have played between their dangerous offense and leaky bullpen and defense was there for all to see in this one.

Back came the bats with a two-out, two-run rally in the bottom of the eighth.

On a night veteran closer Kenley Jansen wasn’t available and Chris Martin had to be used in the eighth due to the struggles of García, Cora turned to Josh Winckowski for the save.

The righty came tantalizingly close to converting his fourth career save and first this season. With two on and one out, Nathaniel Lowe hit a grounder to the second-base hole that Hamilton fielded and relayed to Ceddanne Rafaela for the lead out at second. But before you could say game-ending double play, Rafaela’s throw was a tad high, pulling first baseman Romy Gonzalez off the bag.

Moments earlier, Rafaela had moved from center to shortstop when a right calf injury pulled second baseman Nick Sogard off the field, setting off a series of defensive switches by Cora.

“The throw was up,” said Cora. “I mean, it’s hard to go from center field to shortstop in the middle of an inning. I’m not giving mulligans, but it’s not that easy doing what he's doing. Obviously he expected to turn that double play, but we didn't do it.”

Wyatt Langford stepped up and hammered Winckowski’s 0-1 cutter over the Monster in left-center for an equalizing three-run homer.

After the Sox went down 1-2-3 in the bottom of the ninth, the Rangers took back the momentum for good on the first pitch of the 10th, when Jonah Heim ripped Zack Kelly’s cutter to right-center field for a two-run homer.

“Obviously you felt good going up three,” said Gonzalez. “It wasn't enough. Overall, just a tough loss.”