Point taken but here are the issues with Cauley-Stein:
1. He's going to take time to develop. As is the case with MOST big men. He's pretty raw and probably won't be ready to be a starter until year 3. Much like Perkins, if he ever turns into a Perkins type. Meanwhile, Sanders will be ready to start from Day 1, as soon as we make the trade.
2. He might never reach his ceiling. Instead of getting the next Larry Sanders, we might be getting the next Fab Melo. Sanders is already a proven elite rim protector. Not saying Cauley-Stein doesn't have the ceiling, but it's tough to predict whether a college kid can take it to the next level as an NBA big where everyone is bigger, tougher, faster, stronger, and more athletic.
3. As you already mentioned Cauley-Stein probably won't last until our second 1st round pick. Why gamble on a guy who might not even be there for our pick? I think it would be better to take the most talented guy available with our top pick, trade for Sanders, and use our second rounder on a boom/bust pick. But with our 1st rounders we MUST hit on guys who can contribute right away or are going to be stars for the future. Wiggins/Sanders could give us that foundation to be legit contenders. Wiggins/Cauley-Stein... might see us visiting the lottery for another 3 years.
I'd rather try to move up with our second and snag Cauley-Stein. He seems similar to Sanders, will be way less money and hopefully none of the knuckleheadness that Sanders comes with.
Plus you can mold him into the Celtics style of play. Sanders may fight that more than a rook. Im not sure how well Cauley-Stein's game will translate to the NBA, but if he puts the work in I could see a Sanders/DeAndrea Jordan type center. Hopefully with better FT shooting.