That 2021 pick swap seems meaningless as OKC will almost certainly have a higher pick than Houston anyway. Things are more uncertain in 2025, and Houston wasn’t allowed to trade their 2025 pick anyway (having already included their 2024 and 2026 picks in the deal).
So can a team like OKC trade a pick swap? That would seem weird and I’m not sure how that would even work. But help me see the value in the 2021 pick swap that OKC just acquired...