Simple. Put the right RFA tender on him, and ask teams if they're interested. I'd try to include Welker in a deal to trade up in the draft. Teams that need viable secondary receiving options, or utility players, would love to have him. I can see Cleveland and Washington being interested.
I'm well aware that this isn't Madden. I'm not saying this WILL happen. I'm saying I would LIKE it to happen, as one of many potential draft scenarios. Would you care to explain why such a deal is not probable, instead of whipping out the overused "this isn't Madden" brush-off?