Dombrowski, who has a lengthy history of making bold and creative trades in his 27 years as a general manager in Montreal, Miami and Detroit, conceded that his sixth trade with Cashman — another three-team deal that sent pitcher Shane Greene from New York to Detroit so that Cashman could acquire shortstop Didi Gregorius from Arizona — could be their last for a while.

“I would assume that would affect us some,” said Dombrowski, who was hired by the Red Sox after being fired by the Tigers in August.

It was the same for years when Theo Epstein was the Red Sox’ general manager. Though he and Cashman had an easy relationship, occasionally sharing the stage at baseball symposiums at small colleges in the Northeast, Epstein said that only once, early in his tenure, did they talk about a trade — and it was half-joking at that: Shea Hillenbrand for Nick Johnson.

“But nothing ever came of it,” he said.

Epstein, now the president of baseball operations for the Chicago Cubs, said it was similar to his dealings with his current rival, the St. Louis Cardinals.

“We have less dialogue with the Cardinals probably than any other team, and in Boston we had less dialogue with the Yankees than any other team,” Epstein said. “It’s just common sense. Obviously, the key is to focus on what you’re getting back for your club, but it would do a lot of harm to the organization if the deal backfired on you and hurt your own club and helped your rival beat you on the field at the same time. It’s sort of a double penalty, so you have to be pretty fearless to embrace that.”

Baltimore Orioles General Manager Dan Duquette described the perils of trading within the division this way: “If you’re not right on the transaction, you’ve got to look at your mistake for 18 games a year.”

Some places, though, are more perilous than others. The American League West seems to be an especially welcoming place, with the teams separated by great distances and the fan bases and media markets not so rabid. Jerry Dipoto, recently hired as the Seattle Mariners’ general manager, made trades with every division rival in his three and a half years as the Los Angeles Angels’ general manager.