The streak of dominating starts was going to end at some point for the Red Sox. It just happened to fall on Ryan Dempster’s day, and that “close but no cigar” trend has been fitting so far for the veteran pitcher in the beginning of his Sox career. Dempster was solid enough to get a victory, but he got tripped up by one bad inning to end the Red Sox’ seven-game winning streak and record-setting start to the season from a renovated rotation in a 4-2 loss to the Kansas City Royals in the first game of yesterday’s day-night doubleheader at Fenway Park. The four runs allowed by Dempster (0-2) marked the first time a Red Sox starter allowed more than three runs in a start this year. The Sox tied the American League season-starting record of 16 consecutive games, held by the 1978 and 1981 Oakland Athletics. Dempster gutted his way through seven innings, allowing the four earned runs on six hits. He also struck out eight, continuing impressive numbers as he joined Pedro Martinez (1998) as the only Red Sox pitcher to record seven or more strikeouts in his first four starts for the team. Remarkably, yesterday was one of the worst starts by a Sox pitcher this season. When one considers that the performance would have been deemed well above average last season, it shows that the rotation has far exceeded expectations thus far. “We push each other to get the best out of each other,” Dempster, who now owns a 3.38 ERA, said. “Our job is to go out there and give quality innings and get us a chance to win a ballgame, and that was the case today. Just came up short. . . . We have been playing really good baseball, and we played really good baseball today.”