A decent backup is looking for the chance to be QB1 and get a lot more money. The Joneses have done nothing but keep backing Dak and talking contract extension. If they do extend him, think they're going to let Garrett get the hook? They are so much more about how it appears to be than it really is no way they're admitting another mistake.
A "justa backup" is going to be nothing more than that and none of the players on that left side have proven they're a QB1 that can sustain that.
The best path, and I do not think they're going to take it, is to let Dak play out the final year of his contract and decide at that point what to do with him. They've shot their mouths off too much about him getting extended and being the answer that they have to do something this off season. There are some good looking QB's coming out in 20 and I've not seen yet whether Herbert will come out in 19 or wait a year.
With guys like Tua, Murray and Lawrence and maybe Herbert in the wings, they have the luxury of waiting until 20 but if they give Dak even high Tier 2 QB money, they're committed. They do that deal, no way they can bring in competition like that and I tell ya, I'd take any one of those QB's over Dak.
And before a Dakster goes off on me, most of that stems from them not putting the right complimentary players around any QB since Aikman and that was not this group that did that.