When Cleveland rightfielder Shin-Soo Choo doubled off the centerfield wall Thursday night at Progressive Field, Austin Jackson appeared to have no option other than retrieving the ball and keeping Choo from third. But with Jackson's speed and improving arm, he nearly threw out Choo at second. "The throw," said Tom Brookens, the Tigers' outfield coach, "was right on the money." Few centerfielders get a better break on a ball than Jackson. And few are as fast. Until recently, however, Jackson hasn't displayed much power with his arm. Brookens said Jackson's arm began to improve last season when he began to change Jackson's mechanics. The centerfielder was holding his hand and arm too high over his head as he coiled it back. This position took away torque. So Brookens had Jackson move his arm slot farther to his side.