BOSTON – The Twins have discovered an ingenious solution to their Jose Berrios problem: Judge him by the balls that don't get hit hard.

Mookie Betts ambushed the Twins righthander with a pair of first-pitch home runs to stake the Red Sox to a 4-0 lead. Berrios allowed two more runs over five-plus innings, and Minnesota limped off with a 6-2 loss at Fenway Park. Minnesota shed a game off its AL Central lead, now 5½ games after the Indians held off the White Sox.

It was the latest post-All-Star frustration for Berrios, who owned a 3.00 ERA before the break and a puzzling 5.37 ERA after it. But if there's a pattern, the Twins say they don't see it; if there's any cause for alarm, it hasn't penetrated the Twins' clubhouse.

"He's been throwing the ball really well on the year and as of late, and he did a lot of things well [Wednesday]," Twins manager Rocco Baldelli said after Berrios surrendered eight hits, issued three walks and recorded 15 outs. "His stuff was really good. He was crisp. He made a lot of pitches and executed the way he wanted to."

Well, perhaps not to Betts, the reigning American League MVP who is having a pretty solid follow-up season. The outfielder was clearly waiting for a fastball over the plate on Berrios' first pitch, and when he got it, he skied it into the Green Monster seats, a jolt to open Berrios' night.

An inning later, after a Christian Vazquez single and a walk to ninth-place hitter Jackie Bradley Jr., Betts was lying in wait again. Here came a curveball, center-cut, and there it went, more than 400 feet over all three rows atop the wall. Suddenly, 10 Red Sox had batted, four had scored, and the game already felt all but over.

Berrios stuck it out for three more innings before allowing the first three hitters to reach in the sixth, with Vazquez serving a run-scoring double down the left field line to knock the righthander out of the game. But Berrios said he wasn't discouraged by picking up his eighth loss of the year. He agreed with Baldelli: Everything is fine except the results.

"Right now, I'm missing a few pitches here and there," Berrios said after falling to 0-3 in three career Fenway Park starts. "We're not making any big changes or anything like that. It's just going out there and trying to locate my pitches better."

Video (02:02) Twins righthander Jose Berrios says, through interpreter Elvis Martinez, that Mookie Betts was waiting on first-pitch strikes, and missed locations allowed him to hit them for home runs.

In one way, he's right — there is plenty of time to recover the form that has made Berrios a two-time All-Star. Three-plus weeks remain in the season, and he showed signs of righting himself last weekend in Chicago.

But the playoffs are approaching, the Twins aim to be involved in them, and they need Berrios to pitch like a Game 1 ace.

Baldelli sounded confident that Berrios will be there when the Twins need him.

"Was it his absolute best, most crisp start of the year? No," Baldelli said. "But he threw the ball well for long stretches, and you don't miss bats like that against a good team like the Red Sox by mistake, by accident. He threw the ball fine."

Just not as well as Red Sox lefthander Eduardo Rodriguez, whose own first inning also revealed the sort of night he would have. Rodriguez used a changeup to whiff Max Kepler, blew a fastball by Jorge Polanco for another strikeout, then caught Nelson Cruz looking on another inside fastball.

From there, Rodriguez, who has allowed 22 home runs this season, limited the Twins to nothing but singles. He departed after allowing five singles in seven shutout innings, striking out eight and inducing two double plays. The Twins left the bases loaded in the fourth inning after a pair of Rodriguez walks, but Willians Astudillo flew out to right to end the Twins' biggest threat.

Only after the lefthander departed did the Twins' power-hitting lineup finally show up. After Cruz singled to open the eighth inning, Eddie Rosario, who had not homered since Aug. 18 — 60 at-bats ago — connected off Red Sox reliever Ryan Brasier, his 28th homer of the season.