For the second time in this three-game series at Fenway Park, an emergency starter came up big for the Blue Jays. On Sunday, in a 12-4 win over the Red Sox, it was 25-year-old right-hander Chad Jenkins, filling in for Brandon Morrow, pushed back to Wednesday nursing a sore back and spasms. Jenkins worked five effective innings, plus two batters into the sixth, allowing just a homer to Mike Napoli and throwing 90 pitches before lefty Aaron Loup took over. When Morrow returns to the rotation later in the week, they will not need both Jenkins and Ramon Ortiz. “Jenkins has a good arm,” Jays manager John Gibbons said prior to the game. “The organization’s high on him. He’s coming in to fill a spot today so we really don’t know what to expect, But he’s got a good arm and we think he’s got a bright future.” The victory gave the Jays their first winning road trip, going 4-3 in Tampa Bay and Boston — and only their second series win overall. The first was in Kansas City, April 12-14, the weekend Jose Reyes was injured. The Jays are now 8-12 on the road and return home for a pair vs. the Giants. The slumping Red Sox, minus their top two closers, have lost eight of the last 10. But even more encouraging for the Jays on this day was that some of their more suspect bats came alive again, especially those of the seldom-used Emilio Bonifacio and shortstop Mune Kawasaki whose two-run single on a grinding at-bat opened the scoring in the second. The most surprising among the Jays’ five homers was the one by Bonifacio, whose fence-scraping two-run homer just eluded the glove of Shane Victorino, who crashed painfully into the fence in front of the Jays bullpen. Bonifacio had three hits in the game, including a double.