Felix Doubront received his first taste of World Series pressure in May. The promising left-hander had just been skipped in the starting rotation after a dreadful six weeks that were exacerbated by his failure to arrive to spring training in anything resembling peak physical condition. The only thing doughier than his body was his ERA: 6.40 on May 16 before a road start against the Tampa Bay Rays. Like a cornerman telling his fighter he’s losing on the scorecards and needs a 12th-round knockout, Red Sox pitching coach Juan Nieves addressed Doubront starkly. “This is the biggest start you will ever make in your life,” Nieves said. “This is your World Series.” The numbers may not reflect it — he walked six — but Doubront showed the Sox something that night. Doubront allowed three hits and two runs in five innings, challenging hitters, keeping his fastball down and striking out seven. He earned back his spot in the rotation and then became the first lefty in franchise history to make 16 straight starts without allowing more than three earned runs. The end of Doubront’s season? A mixed bag. He finished 11-6 with a 4.32 ERA and made the playoff roster in part because the Red Sox had no one else. He didn’t help his cause by questioning whether he could pitch in relief. The odds of seeing him in anything other than a blowout appeared remote. And so it went. Doubront idled during the AL Division Series. He made two shutout appearances in the AL Championship Series with the Red Sox trailing big. But now the World Series is here and the narrative has come full circle. Doubront is proving he learned the lessons of May, because he is once again a factor. He tossed two scoreless innings in Game 3, giving the Red Sox a chance to rally for a 4-4 tie before the crazy obstruction call ended a 5-4 loss. He was even better, all things considered, in Game 4, entering for Clay Buchholz in the fifth and departing with two outs in the seventh. The bullpen allowed an inherited runner to score, but that was the only blemish on his 22⁄3 innings. He struck out three, earned the decision in a 4-2 win and emerged with a 1.93 ERA for the Series. He has allowed two hits and one walk. As far as rebirths go, this one has proven pivotal. “Gosh, he’s been efficient, he’s been throwing a lot of strikes,” manager John Farrell said yesterday before Game 5. “What stands out in this environment (in Games 3 and 4) is just the poise and the comfort with which he’s attacked the strike zone. It’s been something we’ve desperately needed.”