Gerrell Robinson, who was also cut, played better than King. He's bigger and stronger (6'3" 227 vs. 6'0" 190) than King, slightly slower iirc, but gets stone hands from time to time. King is fast, and is somewhat of a dynamic playmaker, but seems to have a lot of drops. They are both developmental to a certain degree, as they were UDFA and a 5th rounder. They were just buried under the weight of our WR depth. So they are prime candidates for the practice squad if they escape a team snapping them up. I'm not sure if anyone will though.
As far as Painter, he's real raw. He's a big, strong, guy, 6'6" 309, but has poor technique. He's practice squad material 100%, he needs more time in the oven so to speak. I think he could be solid depth given a year or two of work. No where near a starter at this point.