Right, but having a QB making 25M+ makes it more difficult to build a good team around the QB. Unless you have an elite QB, who can compensate for deficiencies elsewhere, you're better off trying to win with a QB on a rookie contract. Of course, if you can't identify good players, it doesn't matter either way.
While I agree with your premise, it think you have to look at it on a bigger scale. It all goes back to your avg payscale post you made a couple of months backs( Not sure where exactly, but Im 100% you're the one who posted it).
That list of position and their avg salary is where it all starts. In a perfect world, you'd like to have positions at the top of the list playing on rookie contracts. QBs, DEs and DBs IIRC. This is where you get the most bang for your buck. Problem is QB is much harder to hit on because they rely the most on their surrondings for production, as opposed to DEs and DBs who are much more likely to provide results based on their skills regardless of their peers. In other words, they are often left on an island.
Anyhow, I dont see Tannehill's contract as a problem *right now*, because Fins simply havent been able to draft players that should get big 2nd contracts... X. Howard, and Fitz might change that but even then, paying a QB 25M per shouldnt prevent you from signing them. That figure has pretty much become league average, which is pretty much what Tannehill gives you pruduction wise.
Keep building the team through the draft, hit on high value position players, all the while looking for your QB, once you identify him, then you make your move... Fins are simply not at the point where better QB play makes them a contender, so whats the rush here?