While I dont disagree with your opinion of Tannenhill (he probably falls around 15-18 which is not necessarily a $100 Million player) the more important question is what would you do with him then?
If you disagree with the kapernick and dalton deals as well, would you have let them simply become unrestricted free agents? Because there is ZERO chance those guys would not have received comparable money in the open market.
Look - i agree, none of those guys are currently in the top 15, but what do you do. Let kap/dalton walk, get nothing in return and then draft someone? There is a far greater chance of finding a blaine gabbert (while also losing out on drafting a position player) then there is finding an aaron rogers at some point in the first round.
Being a GM with these middle of the road QBs is almost impossible. Even flacco - many people think his contract is the worst in the NFL, but in my opinion, $17 million for a guy who you know will have you at least in the hunt for 10 years is not too much to pay.
It's an Alex Smith situation, IMO. Dont you think? Alex Smith was the top rated QB in the NFl under harbough, he still didn't (doesnt) have "it." maybe you milk it along but keep drafting QBs high until you can move on...that's what i would do. They should be drafting QBs annually in the top 4 rounds (every team should honestly). They should be looking for the next guy constantly...
...yes, I may let him go as an unrestricted free agent anyway. he's good enough to get you to 8-8 or 9-7 annually, like Jay Fiedler, but you can look at the guy and see, he's not Aaron Rodgers, nothing about what he does is "special," not even glimpses like Bridewater had last year or Wilson gives you, or big ben, or Rivers when he carved up the Pats and Seattle...you dont see something special, you dont have something special...I'd consider letting a QB walk as an unrestricted free agent if you feel the best you'll ever be with him is...10-6 and a wild card team.
Dont they move on from coaches with the same issue?