Tasteless Beaver
PLANE TEAM GOOD
By the time you're outside of the Top 10 the likelihood of hitting on a pick drops off dramatically. Moving from 20 to 13 in a consensus weak draft isn't going to take a massive payment. A 2nd round pick is a fairly respectable return for dropping from a mid-1st to a lower-mid 1st. It's not like you're dealing a 2nd to go from #20 to #5. Include a 3rd or a low-level prospect if it's not enough. It won't take both 1sts if it were to happen.
Last year the Jets swapped a 2nd for a 3rd to move up 4 spots from #22 to #18. The Coyotes dealt a 2nd and Joe Vitale to move up 4 spots from #20 to #16, and they took on Datsyuk's contract in the process.
Your cases lack context. Jets basically traded 22 and 36 (early 2nd) in a deep draft for 18th and 76th (I think?). Trading 20 and 27 is a slightly larger payment vs 22 & 36, but the jump from 18 to 13 is a lot bigger. There is better value for the Blues to get 13 (and a 3rd), vs. what the Jets paid for 18.
And the Coyotes took on Datsyuk's contract to hit the cap floor - that contract became an asset to them. They needed the cap recapture to spend cap money without spending it, basically a bad form of draft asset control to save $$$.