Complex sentence: Since the completion of the 1977 season the clubs fortunes have taken somewhat of a slide and in the thirty years since then the club has only managed a sole French Championship in 1992 and two Lord Derby Cups in 1982 and 1989.
Split into simpler sentences: Since the completion of the 1977 season the club's fortunes have taken something of a slide. In the thirty years since then the club has managed a only a single French Championship in 1992 and two Lord Derby Cups in 1982 and 1989.