I'm really putting a long, athletic defensive player up on top of my list. I still think, come playoff time this will be the Lakers achilles heel. They have no one to counter any quick athletic wing players.
Green, Bradley, KCP are either too short or a step slower. I can foresee PG/Kawhi feasting on us come playoff time, ditto with the Bucks.
RoCo for Kuzma, Bradley and Troy Daniels works. I'd even dangle THT to replace Troy to sweeten the pot.
If they can somehow swing that and then add Collison, I'd be very confident about their title hopes this year. A versatile defender that can guard 2-4 would be tremendous.