NEW YORK – It has happened before, that's the really annoying part for Tyler Duffey. Two years ago, he stood on this same mound in a late September game, got two strikes on Didi Gregorius, and went with a high fastball, hoping for a swing and a miss.

Gregorius homered.

"Learn from your mistakes," Duffey said he told himself, and on Friday, he proved he had. He got ahead of Gregorius, went with a high fastball and whiffed him.

So what happened Saturday? "I just didn't get it high enough," Duffey said of the pitch that buried the Twins, a pitch that Gregorius walloped into the seats in the right field corner for a grand slam.

"He's taught himself, he's adjusted to the league, and he's got an approach that works pretty well. And I just missed my spot."

There's been a lot of that from the Twins' pitching staff, especially their bullpen, over the first two games of the postseason. Minnesota won an AL Central title in large part because its bullpen was one of the most reliable in the league, particularly in the second half of the season, but it hasn't played out that way in October.

Maybe it's nerves, maybe it's the Yankees' approach, maybe it's the Yankee Stadium crowd, but Twins relievers have yet to hit their spots with any regularity. In two games, the bullpen has been handed 10 innings to cover, and they haven't done the job: 11 runs on nine hits plus a whopping 11 walks. That's a 9.90 ERA, and the difference between competitive games and blowouts.

"I don't think it's our approach as much as it's probably just execution out on the mound," Twins manager Rocco Baldelli said. "Our pitchers have been pretty good with their strike-throwing. Except for a few aberrations, there's really nothing that I can point to or any reason for it."

The walks stand out in particular, because they're so out of character; the Twins' bullpen surrendered fewer walks than any pen in the majors except Cleveland's.

But the Twins have walked eight Yankee hitters in each of the first two games, and hit a batter in each.

The last time Minnesota issued eight walks in back-to-back games? May 10-11, 2011.

"There's nerves going, sure, but we're facing a great lineup," explained Cody Stashak, who walked Gregorius four innings after his grand slam. "These guys, they weren't biting at anything. They weren't chasing, they're just sitting on strikes."

A Yankees batter drew a walk in seven of the eight innings on Saturday, and while only two of them scored — in fact, the bullpen limited New York to only one hit over the final five innings, albeit after the game was decided — the game might have been different if Twins pitchers had attacked the strike zone more aggressively.

Then again, that's what Duffey tried to do, and look how that turned out.

"Pitching here, it's adrenaline. … I was ready to go," Duffey said after relieving Randy Dobnak with the bases loaded in the third inning. "It's unfortunate that tonight went the way it did."

Here's how it went: After Giancarlos Stanton lifted a low slider deep into center field for a sacrifice fly, Duffey got two quick strikes on the next three hitters in a row. Which is great, considering he had allowed only four hits all season after building an 0-2 count.

But Gleyber Torres singled in a run. Duffey hit Gary Sanchez with a pitch. And Gregorius?

"You literally have to throw it at his eyes. Because he made that adjustment, I think he got worn out by them and finally figured out how to get to the high ones," Duffey said.

"In retrospect, I would have liked to throw it higher. It's just kind of tough to chew on, but I won't make that mistake again."

Phil Miller covers the Twins for the Star Tribune. phil.miller@startribune.com