a guy from another team doesn't mean he's a make for your team. These guys are not cookie cutters....Some edge guys emerge with help from others around them. Without certain players around them they don't perform as well. Sure, and I mean for sure guys cost a TON of money.....
To say that a rookie edge can't play as good as a vet just isn't true, any more than any other position on a team. A FA vet is not a lock to do anything any more than a 1st round pick is assured to....
Unless you think it's just the edge position that is better off with a vet over a rookie.....because it seems your rationale would work for every position and it would be better if teams stayed away from draft picks as much as possible to assure better play.