Ironically it was Patrick Duffy's return in the following season which probably helped to nix the Wes is Jock storyline. You are indeed correct, the character of Ben Stivers only appears in a few episodes toward the close of season 9 (DVD count). When Duffy decided to come back and it was also realised that the Wes is Jock storyline wasn't working out with the viewers, the Producers realised that there was effectively two resurrections from the dead in that season. Bobby coming back & Jock coming back too! That may have had an impact on the storylines as they probably thought two resurrections wouldn't be believable! So in effect Patrick Duffy's return as Bobby had quite a detrimental effect on that years storyline of Wes being Jock. If Duffy had not have come back it's highly likely that the Ben Stivers character from season 9 would have turned out to really be Jock Ewing.