That and the fact that they could potentially win the championship by standing pat. It's also too soon to declare Wiseman a bust. I don't see him being a star in the sense of offensive hub, but a complimentary type one (Ayton) isn't entirely out of the question. Either way, it's worth it to find out.
What would Poeltl change? He's not much, if any more of a deterrent against the Jokic/Embiid types and they'd still start Looney because of his chemistry with their big three. Throw in Green playing small ball five and that leaves spot minutes for another non shooting big.