When the Twins signed Byung Ho Park this offseason, they knew they were getting a strikeout-prone slugger who could regularly destroy baseballs. For about a month and half, he lived up to that billing. Midway through May that changed. He turned into a strikeout prone player who gently hit baseballs.
Multiple explanations for this massive slump were offered. Teams finally adjusted to him. He focused too much on hard fastballs. His confidence was gone. As such, the Twins sent him to Rochester to regain his swing.
If reports are accurate, however, it would appear that, in addition to the issues above, Park has also been playing through an injury.