Derek Jeter, before and after his adjustments: .260/.326/.366 to .346/.444/.423
For Jeter, the change has been shortening his stride, pushing his momentum toward the mound instead of toward the plate, and holding his head more steady.
Curtis Granderson, before and after: .239/.306/.415 to .276/.367/.586
Obviously, keeping both hands on the bat has given Granderson a more consistent swing (making more contact) and more power.
Nick Swisher, who worked with Kevin Long in the offseason, has seen more questionable results: .249/.371/.498 in 2009 to .288/.360/.514 in 2010.
In the "Year of the Pitcher," Swisher's nearly identical line is a 9 point increase in OPS+. His quieter approach at the plate has actually resulted in vastly fewer walks than last year (97 to 56, in exactly 607 PA), even though he's already blown by his career high in hits (156 to 141).
While Swish's aggressive approach has paid off in batting average and an All-Star appearance, he's seen nearly 200 fewer pitches this season in the same number of PA.