Much like players being in competition with each other, GM's are too. It is the job of the GM to put their team in the best position to win. That is accomplished by beating the other GM's when it comes to creating the best roster possible.
How did the Jones screw the pooch? Here is how.
These two quotes were taken from the post 1st rd interview.
This has to do with the trade value of the 18 for 31 and 74 swap.
"Jones disagreed, arguing that the Cowboys "actually did better" on their chart."
"It's a mistake to think that transactions go by any trade chart," Jerry Jones said"
So which is it? Did they win according to their chart or is there no chart?
They clearly gave up 80 points on the trade. But it gets worse. By reaching on a 2nd rd(I'm being generous, he is really 3rd rd) player they left even more points on the table.
31(600 points) vs 47 (430 points) Loss of 170 plus the loss of 80 in the trade = 250 points.
That equals the 4th pick of the 3rd rd (pick 68) just thrown away.