The difference is all of those guys are winners with the exception of Tanny. Flacco has a ring, Dalton and Smith consistently get their teams to the post season.
To me, Tanny, TT and Cutler are all in the same boat because they are better than what else is out there but they aren't perennial playoff guys. It's a different argument when the decision to pay Dalton has the "well he plays well enough to consistently make the postseason, maybe he'll get hot," angle. The obvious benefits are much more prominent.