Complex sentence: Hough was, at the time, fresh from winning his fifth Mirrorball trophy, planning not to coming back to the show, however, he changed his mind when Purdy joined the show as a contestant.
Split into simpler sentences: Hough was, at the time, fresh from winning his fifth Mirrorball trophy and did not plan on coming back to the show. However, he changed his mind when Purdy joined the show as a contestant.