Lakers: The Lakers are 4th in the west with an even point differential. So, they're winning games, but not good enough to be scary. Part of their problem is depth, part of it is defense. This addresses both. Gafford is a real rim protector who could either start over Ayton or spell him off the bench. Keon Ellis is JJ Reddick's dream role player. Schroeder has had success with the Lakers in the past, and would replace the Vincent minutes with more teeth. These are the type of guys the Lakers will need going forward with Luka and Reaves at the helm.
Kings: The Kings suck, so a wholesale shift might be due. Schroeder, Monk, and DeMar are all under contract for the next 2-3 years for absolutely no reason. They all are and will continue to block minutes for the young guys. They all need the ball to be good. So, sending them all out wouldn't hurt. Sending Keon Ellis out might, but getting Rui and a pick swap should be plenty compensation. Klay, Martin, and probably Vincent are likely to stay on the team going forward, but at least they don't command as many on ball reps as the other guys.
Mavericks: The Mavericks have a great trade chip in Gafford, and cash him in for another Lakers first. Outside of that, they exchange two bad contracts for two more. In fairness, the Mavs still could use some ball handling, so Monk would be helpful. DeMar is an expiring next year, and might make Kyrie more inclined to stick around long term. Whatever, the Lakers pick is the draw.