In his original post, Redditor u/Jour4232 acknowledged up front, “I know many say it went downhill after Ziva left but I still really liked the few seasons after that (S11-13) until Tony left. … I feel like the team just became way less fun.” Indeed, the most up-voted response, and many that followed, pinpointed those two departures: Ziva (Cote de Pablo) early in Season 11, and Tony (Michael Weatherly) two seasons later. In addition to admitting that the decline that began with Ziva’s departure accelerated after Tony’s, u/ptazdba pointed out, “The writers just didn’t get it together and develop the new characters.”
This was a common sentiment. “A few things contributed to the downfall,” elaborated u/whatitdewwbabyyyy. Among those: “I don’t think they put enough thought into developing the team post Ziva,” and, “They underestimated the hole Tony left behind (to a degree, it was just as much his show as it was Harmon’s).” Echoed u/vav_tkiah, “Tony was the glue.”
But despite the many responses to this effect, not everyone agreed that “NCIS” has gone downhill at all. “Declined? I wouldn’t say that but it’s definitely not the same,” posted u/hbkjrt14, who also wrote, “Season 14 and 15 were rough. … It’s since found its stride for what the show is now.” U/Anxiousrabbit23 agreed, writing, “Season 14 and 15 were … definitely some of my least favorite seasons. But I LOVED season 16 and 17 as a whole. It’s just different.” It seems that, whether or not they believe it constitutes “decline,” fans concur that the show was fundamentally different after Ziva and Tony departed.