Alex Rios of the Chicago White Sox sports the lowest OBP in the major leagues among players with at least 300 plate appearances, .256. Interestingly, Alex does chase more pitches than usual outside the strike zone, but in general, he swings at strikes more often than he swings at balls. His problem lies in his approach at the plate, and approach that pitchers easily exploit.
In 2011, pitchers work Alex away:
They are pitching to Alex's weak zones.
Alex can hit the inside pitch, but that's about it. Why is that? Look at where his hits wind up:
Alex likes to pull the ball. If you divide the field into third, you see there are almost no hits to the rightfield slice of the pie. When pitchers work batters away, they batters that pull the ball often hit weak grounders. Rios's ground outs look like this:
Pitchers are giving Alex rightfield. Unless he takes the ball the other way, he'll keep making outs at a prodigious rate, and cost the White Sox runs in the process.