Jackie Bradley Jr. knows what we think his 2014 season is all about. And he’s not going there. “You can’t replace a Jacoby Ellsbury,” Bradley said yesterday. “He’s an All-Star.” Nevertheless, someone must succeed the fleet-footed center fielder, and the favorite is the rookie who took spring training by storm last year before big league pitching yanked the emergency brake on his ascent. The Red Sox have been grooming Bradley for this moment practically since drafting him with the 40th pick in the 2011 draft out of South Carolina. He justified their confidence by compiling a .404 on-base percentage during parts of three seasons in the minors. Meanwhile, Ellsbury ticked inexorably closer to free agency, with their paths projected to intersect in 2014. Sure enough, Ellsbury signed a $153 million contract with the Yankees in December, creating the opening the Red Sox hope Bradley can fill. The question is if he’s ready. Rival pitchers developed a book on him quickly last year, pounding him on the hands with fastballs. Bradley developed bad habits as a result, and the numbers spoke clearly. He hit .189 with a .617 OPS, striking out once every three at-bats, and spending most of the season in Triple A after making the Opening Day roster. “It’s the big leagues,” Bradley said. “It’s the best of the best. It’s baseball. You’re going to have your ups and downs and adjustment periods. That time up there, I got to learn a lot. The way this organization is, they’re trying to win right away, and that’s what you want. I had my time to go down there and develop, and that’s what I needed. Hopefully it will all pay off this year.” Assistant hitting coach Victor Rodriguez knows Bradley’s swing as well as anyone in the organization, and the confounded hitter he watched last year wasn’t the one who patiently climbed the ranks in the minors.