The reason we have lost those games is not offense. We lost because of defense. Against inferior players, his defense was bad. What makes that worse is that when you have a shotblocker and shot-alterer like Tacko Fall, you can play much tougher initial D than if you didn't have a guy like that to erase your mistakes making your defense better.
On offense, he'd have to shoot better, against much, much, much better comp and in far fewer tries just to be equal to the players we have.
Add to this, he be playing dramatically fewer minutes and be, at best, the fourth option on offense. Would be as happy and into the game? This is important as he clearly chose the opportunity to The Man over part of a team in a better conference.
All those factors make having him a real question mark. With a definite possibility that he'd be an unhappy player.
If he had been an LD Williams-lite, I'd be agreeing with you 10,000%.