I'd have to favor trading KJ instead of White in a potential Collins deals. Collins would be essentially replacing KJ as the starting 4. As TD mentions above, a KJ + Collins pairing seems to be an odd fit and something tells me KJ's game would suffer in a reserve role, whereas White could excel in that role. However, I am certainly not opposed to moving White in a potential Collins deal since it fills an area of great need, but think PATFO values White a lot more than people think or want to beleive. Versatility and play making is key here, but youth and the timetable of the team certainly favor keeping KJ in this potential trade.
Moreover, Walker wasn't extended in the off season and no team wants to trade for him for a reason. He's a scorer who doesn't score consistently. If his shooting sucks, he's a negative. Murray, White and Poetl can positively impact the game even when they aren't scoring. Hence, why Walker's WAR value is 0.1 and the other three are closer to 5. It seems to be an advanced stat that translates well to what your eyes tell you. McDermott measures as the worst Spur's rotational player at -1.1, which I agree with because he's one-dimensional on offense, can't create for others, and a complete turn style on defense. He's on the wrong side of 30 and would be happy to seem him gone.
It would be great to see the Spurs take a big swing in a trade though. Shake things up.