Some players just fall off a cliff earlier than others. Noah hit that wall right around age 30, which is unusual for a player who had recently been of All-Star caliber, but it happens. Same thing happened to Gerald Wallace. All-Star at 27 (and probably should have been at 25 or 26), and washed up by age 30. Never would have seen it coming for either. Sure, they could have been past their peak, but to go from star level to unplayable in 2-3 years, without having experienced a major traumatic injury like an ACL or Achilles, was quite surprising for a player turning 30. Same thing happened with Luol Deng too.
Just something to keep in mind when signing players to long contracts who’ve reached 30. You’re starting to reach the danger zone, even if the odds are still in your favor for the early 30s.