This argument will have a couple of assumptions, so do take stock of that.
One - a QB will be there for us to get. This could mean a trade up, which isn't out of the question or scary as recent history shows us it's quite common: Wentz, Goff, Watson, etc.
This assumes Fangio and Elway are both on board, obviously.
This does not technically presume that the QB is a first rounder, although that almost feels like a given. QBs are so desired that guys get taken in the first round who should be second rounders. Etc. Etc. Etc. We all know the drill.
But why a QB? Some argue that it is a way to strengthen the team for the future. I have been beating those drums forever and a day. Still, another consideration is that it might help us win...now. Why? Well, look at the other option, first. FA QB's are few and far between. No one is really stoked for Keenum anymore, for instance. Cousins put up another great season statistically, and I think he's still a fine QB, but missing the playoffs altogether seems...wrong. In short, it's hard to nail it down with the QB for the team.
But, we have seen teams draft a young QB and do well in the standings. Seattle with Wilson, Ben with the Steelers, Flacco with the Ravens, Watson with the Texans, etc. The point is that each situation was a little different, but in all of those instances, a great defense, or a defense becoming great, was there. And this is where the rookie QB truly shines.
Why? Because that rookie contract....girls and boys...that's what dreams are made off. If your rookie QB is good, whether that means good for the situation, good compared to other rookies, or just having a flat out good season as a QB, you are getting insane value. QB costs are massive. Not to pick on Keenum, but even his average salary, for a QB, takes up a chunk of the cap.
So, if you get a QB to overperform, even if it means smoke and mirrors from a coordinator, a great defense putting them in a situation to succeed, and a running/short passing game that keeps the QB on schedule, you can do well. This leads us to a hidden presumption: we all feel pretty good about expecting Fangio, a defensive genius to shape the defense up a bit and smooth out the edges. Yeah, we have some questions in the secondary, but this team tends to find secondary players, especially corners pretty well. It's a gamble to say "oh we'll be good next year on D," but not all gambles are dire. It's the rest of the team.
The offensive line was average - people will dispute that, argue against it, and I get it. It wasn't pretty. But you have to compare the line to other lines this season. Not what good line play used to look like - the college game doesn't develop OL very well anymore. It's an uphill battle. The WR corp looks promising, but it's young. And unproven. Sanders' injury, one which has really taken a toll out of athletes in the past, is worrisome. There are no tight ends, either. The offense is the biggest issue on the team.
Yet, the line has improved, we will have a good coach there in Munchak, assuming we can hire him. There's hope there, and maybe just maybe you sign a veteran WR/TE as a solid stopgap. Not everything needs to be drafted.
But, the real argument isn't even that the QB builds out into the future. Nor is it that a young QB can be cheaper and better alternative to veteran retreads in the short term...it's that it can do both. And if the rest of the roster does struggle to fit together during the early years, the QB develops and we have more chances in more FA periods/drafts to fix the roster.
I think drafting a QB is the smart play. If Denver thinks a guy is worth taking, get him.