Imagine this scenario...
You're given $750K and told to go out and spend it on a home. The home you purchase can be as lavish as you want, in any location you choose, or as inexpensive as you want. The only caveat is any remaining money leftover after you purchase the home is not available to you. It's gone.
You go out. The real estate market is your oyster. However, you decide to buy a simple turn-key 1 bedroom/1 bath, 1,000 SF home for $130K on a small lot with limited potential for any future additions. You rationalize "well, all I really needed was a roof over my head and it gets the job done." The remaining $620K leftover is taken away.
That's roughly analogous of what the Cowboys did drafting a 25-year old blocking TE with the #58 overall pick in the 2nd round.
People can try to rationalize the pick but it was a waste of a commodity (high draft pick). It was bad value.