People overvalue picks. What's the chance that you hit on any 2nd rounder in the first place? Less than 50%. At QB? A lot less than that.
If you do hit on your guy, you have the guy for 4 years on that rookie deal before you have to resign him. If you're a contending team that lacks a QB, your entire roster is backed up because of that one position. And what realistic options are there our there for addressing it? A top 5 pick in most drafts? Way too expensive for most contenders, and not all that helpful this year anyway. Jimmy Garropolo? That's going to be an Osweiler-sized deal when it happens, plus it's going to cost you picks. And you're not sure the guy can play. Kaepernick? Cutler? Broken bones and all, Tony's a much better bet than either of those guys.
It's hard to say how many years Tony will realistically have left. His injuries have been to bones and not joints, though. That's actually something that gives me a bit of comfort if I'm trading for him. He's a big draw for teams, too, because, say what you want, He's a top NFL personality. He's a safe bet to blend into the roster well. He'll add interest to any NFL season. He's kind of a no-brainer if you need a QB. And all it takes is one owner to want the QB position filled and a little interest added to the 2017 season among the 5-6 teams capable of contending that are floating around out there. Sure, if nobody has enough interest to flip a pick it's pretty obvious Dallas doesn't keep him. And, sure, Jerry's not going to let Tony be in a bad position again no matter what anybody thinks he has a right to do. But if you're BUF or AZ or even KC sitting there looking at what DEN might do as the front-runner in a FA market, if you want the guy, you're going to call with a pick. Maybe you think the compensation should be lower--a 4th, for example. That's fine. At that point a market has been established and it's whatever the market will bear. If you're AZ, though, and want him and BUF has a 4th on the table, you're probably going to make a move.
Put in Cowboys terms, what Romo meant to this team compared to what J Smith, Gregory, Lawrence, or Escobar have meant...it's kind of a no-brainer. Even for a two year window.