The pump fake jokes are always funny, but lets look at the facts since he broke up the big 3 up until Horford, Kyrie and Gordon left:
2013: Traded Doc Rivers for a 2015 1st (RJ Hunter) - Bust, but still got a lotto ticket for his coach
2014: Drafted Marcus Smart - Win
2014: Traded Dwight Powell and Rondo for Jae Crowder, a 2016 1st (Guerschon Yabusele) and a $13 Million trade exception - Coin Flip
2015: Traded Jeff Green for a 2020 1st (Aaron Nesmith) - Early, but definitely a Win at the time)
2015: Traded Marcus Thorton and a 2016 1st (Skal Labissiere) for Isiah Thomas - Win
2015: Drafted Terry Rozier - Win
2016: Drafted Jaylen Brown - Win
2016: Signed Al Horford - Win
2017: Signed Gordon Hayward - Win
2017: Traded Markelle Fultz for Jayson Tatum (1st for 3rd) and Romeo Langford (2019 1st) - Win
2017: Signed Aaron Baynes and Daniel Theis - Wins
2017: Traded IT, Jae and Collin Sexton (2018 1st) for Kyrie Irving - Win, even thought Kyrie didn't work out.
2018: Drafted Robert Williams - Win
Like, I dunno what people expect out of a GM, but I don't see a lot of fails in there. Hayward got hurt, left for more money, Hordford left for more money, and he cashed in on Kyrie who chose not to stay. I get not being thrilled with how he tried to build this roster around the talent exodus, but that's a pretty baller track record in my mind.