Just take Dallas' draft pick over most of the last 10 years and you'll see that even where they were drafting from they were in easy target (picking in their spot or a tiny trade up) position to get a franchise QB.
It is not a must to get one on the top 5.
Most of the Super Bowl winning QBs were not, actually.
9 of the last 11, actually were NOT
Just drafting normally, the could have had Rodgers, Brees, Roethlisberger, Flacco, Wilson, Carr,
etc, etc...the list goes on. Just drafting in a normel draft spot. Saying this is some limited chance is wrong.
HOWEVER, I do agree that if Dallas thinks this guy is a 98--Luck and Rodgers had that rating--and not a 91 (Goff and Wentz' ratings) out 100, then yes, it may be worth it even if you do risk playing him 2 years and him leaving for FA.
But yes IF they think he is off the charts...ok.
They just have to flat out love the player to cough all that up. It's really like giving up 3 mid 1st rounders because the current 4th overall is worth about two current mid 1st rounders.
And unlike the Rams or other teams, this is for a player they HOPE is a backup for 3 years or more.