Griff is a pretty good GM but made mistakes. Lack of cap flexibility or draft picks moving forward, that's on him, it's not something he inherited. He was too complacent with last year's championship team. It wasn't a surprise we would have to match up with GS+Durant in the Finals this year. The problems with this team in terms of matching up with GS -- too old/unathletic, not enough plus defenders, no one to guard Durant, lack of a bench, inability to function without Lebron on the court -- were clear enough and the Finals outcome was predictable.
It is tough luck though because in a "normal" NBA and with decent injury luck this is a team that would have three-peated -- we would have beat GS in 2015 with Kyrie/Love, and would have beat them this year if they didn't have Durant.
Going forward, he needs to break his addiction to elderly three point shooters who can't defend and build a more balanced team, if that's possible. And we need to take risks to get a two-way star in here, a Butler or a Paul George.