This is not Aaron Barrett’s tweaked delivery. (John McDonnell/The Washington Post)

Aaron Barrett’s delivery has been the same for three and a half years. With his back foot on the rubber, he brings his arms toward his chest and sets his left foot even with his shoulders. He then brings his arms again toward his chest, but moves his left foot out, the last step before he throws the ball. During Monday’s game, home plate umpire Joe West called him for balk for the first time with a runner on base in the eighth inning.

West called him for a balk for moving his arms to his chest and appearing to come set twice. Barrett and Manager Matt Williams were confused with the call. They had no choice but to adjust.

Barrett changed his delivery on the fly that night, and it didn’t help; he allowed a single and a run scored on a wild pitch. “I was basically coming set but I wasn’t making that second tap so was mechanically off and rhythm was all out of whack,” he said.

Since then, however, Barrett thinks he has found a way to alleviate the problem.

For the rest of the Rockies series and whenever West is part of a future umpiring crew, Barrett said he would change his delivery with men on base. The modified delivery involves Barrett bringing his arms to his chest only once and moving his left foot once before he throws the ball. But with any other umpiring crew, Barrett said he would pitch like he always has.

Barrett, who is in the midst of a stellar rookie season with a 1.93 ERA over 28 innings, has worked on the abbreviated delivery the past two days. The change isn’t easy to make mid-season, especially after throwing that way for so long, but he said he would manage.

“It feels better,” he said. “It feels fine.”

Barrett said the Nationals even petitioned the MLB office in New York to review the situation because West has been part of an umpiring crew two previous times when Barrett has thrown but wasn’t called for a balk until now.