In his red-shirt year last year he played on special teams vs. PSU, PU and Maryland. He could be a major special teams piece this year, and this move to the defense side could benefit him (e.g., more confident open-field tackling) in that role.
I'm pretty sure CTA will not abide another year of special teams play like he had his first two years. Now that he has liberated himself from DC duties, he will have more time to focus on special teams, among other areas. This move with Pechac could be an example of how he is addressing special teams issues.