Miley gave up a solo homer to the second batter he faced, and allowed another one six hitters later to drop his third consecutive decision in the series opener at Rogers Centre.
Miley, who doesn't typically struggle with the long ball, having given up only one over his last 10 starts dating back to last season, was on the hook for two in two innings vs. the Blue Jays. It was the first time he allowed multiple homers in a game since Aug. 10, 2014, a span of 13 starts.
Josh Donaldson went yard to left to make it 1-0 in the first before Chris Colabello went the other way over the wall in right in the second to spot the Blue Jays an early 2-0 lead.
Red Sox manager John Farrell said save for those early mistakes, he thought Miley pitched well against the predominantly right-handed-hitting Blue Jays lineup.
"The way we're going right now, offensively, two runs seems like a big gap, to be honest with you," Farrell said.
Miley's run support average is the lowest among Boston starters, sitting at 3.18 runs per game entering play Friday. The Red Sox offense could not produce against Blue Jays starter Aaron Sanchez, registering only two hits over seven-plus innings.
Boston squandered a golden opportunity in the fourth after Sanchez walked two to lead off the inning before hitting Allen Craig to load the bases with nobody out. But Blake Swihart went down looking before Xander Bogaerts grounded into a double play to end the inning. That set off a string of nine straight outs for Boston hitters between the sixth and eighth innings.
"It's disappointing to have a bases-loaded, nobody-out situation and come up empty, but to me, I can't say the at-bats are given away after that," Farrell said. "We're still grinding, getting after it."
The Red Sox were 0-for-7 with runners in scoring position on the night, and 4-for-43 in that category dating back to May 3 -- a span of five games.