BOSTON – Just minutes before the midnight deadline on Wednesday to add players who can be eligible for the postseason roster, the Red Sox acquired first baseman/outfielder Conor Jackson from the A’s. A right-handed hitter, Jackson gives manager Terry Francona another option in the corner outfield spots.Jackson will be in the mix with fellow right-handed bat Darnell McDonald and lefties Josh Reddick and J.D. Drew, who was to be activated from the disabled list (where he has been since July 20 with a left shoulder impingement) yesterday. But a sprained right middle finger suffered in his rehab game Tuesday night with Triple-A Pawtucket has set Drew back for about a week.Francona’s challenge will be finding time for all of them, especially Jackson and McDonald. In 61 games, McDonald is batting .195 with five home runs, 18 RBI, 30 strikeouts and 11 walks. He is hitting .146 with no home runs and five RBI against right-handed pitchers, .220 (five, 13) against lefties. In 102 games with the A’s, Jackson hit .249 with four home runs and 38 RBI. Against right-handers he is hitting .246 with four home runs and 28 RBI in 89 games. Against lefties Jackson is batting .254 (0, 10) in 55 games.”If something were to happen in September, say to Mac and we don’t have somebody, that’s not good,” Francona said. “How we fit both of them in, some of it’s probably going to be determined how they swing the bat. There’s no getting around it. How you figure that out and how you let a guy get hot enough where they can swing the bat will be our challenge and we’ll work on that.”Jackson has played first base, third base, left field and right field.”Whatever they need,” he said. “It’s probably going to be a bat off the bench and here and there playing against left-handers. Whatever my goal’s going to be or whatever my role is going to be I’m going to be ready for it and be prepared.Jackson, who turned 29 in May, was a first-round pick (19th overall) by the Diamondbacks in the 2003 draft out of the University of California. He has appeared at first base more than any other position, 384 games, but has played primarily left in the outfield. This season, though, he has appeared in 28 games in right field and 20 games in left for the A’s.”I’m comfortable [in right field],” he said. “I’ve played quite a bit this year and I think it’s getting to be as comfortable as left.”Jackson has struggled over the last few seasons. In 2006, his first full big-league season, he hit .291 with 15 home runs and 79 RBI in 140 games, with an .809 OPS. Overall, in his first three seasons, he hit .292 with a .451 slugging percentage and .371 on-base percentage, averaging 138 games.After his rookie season, he hit 15 and 12 home runs, respectively, in each of his next two seasons. But in the next three seasons, Jackson, who was traded by Arizona to Oakland on June 15, 2010, has hit just seven homers in 192 games, while batting .234, with a .314 OBP and .323 slugging percentage.He contracted Valley Fever in May 2009 and lost about 35 pounds from his 6-foot-2 frame. His last game for the Diamondbacks that season was May 11. In 2010 he appeared in 60 big league games, 42 with Arizona and 18 with Oakland, spending time in the minors in both 2009 and 2010.”I think for me it was when you miss so much time and you’re getting better every single year, like I felt like I was, and then 2009 hit and I got sick and last year I missed quite a few games with injuries,” he said. “When you miss that many ABs you put yourself behind the eight ball pretty much. It’s just pretty much getting your feet back under you and getting in touch with your swing again.”Obviously, I got about 300 ABs [368 this season] but I feel I probably need some more, whether it’s going to play winter ball or whatever. But I feel like I’m, healthwise I’m fine. There’ s no ill effect of what it was.”He’s looking forward to being part of a pennant race.”I think playing in the playoffs is a feeling that’s unparalleled to any as