Making mistakes is part of being a GM- everything is a calculated risk. Cleaning up mistakes is an important part of the job- better than doubling down so you don't have to admit something didn't work out!
Last summers moves were okay (there weren't many options), but we got unlucky with all of them- Noel and Rose got injured, Randle had an absolute meltdown. If Noel had performed like the previous season (not a huge ask), his contract would have been fine, could have got a second rounder at the least back. Likewise with Rose. I'm not a fan of extending players a season in advance because you never know what might happen, but at the time Randle's contract was decent even if he had a slight regression.
Worst mistake was $8mil for 2 seasons for Kemba- 1 season would have been fine, or a minimum contract would have been fine, but that second year blew up in our face. Though likely OKC only agreed to the buyout because we were saving them $16mil.