We also have the remind ourselves that Massachusetts making $15 million is less than a good amount of other states. So seeing a guy sign and play here at that number is different than if he signed for that in say Florida. So we can't say Mitch is overpaid. He is at market. Even Queta will be next year.
The millionaire's surtax for $15M income would be $555,000. I think this is overblown. Other states might have higher real estate taxes, more tolls, or other taxes. State taxes are not nothing, and they are high in MA, relative to FLA anyway, but the federal income tax on $15M is $5.5M. If players want to go to ORL or MIA, just to save 3-4%, that is their choice I guess.
As to Mitch-Rob, he is not playing to what I would expect for his contract so far. But it is early. BOS paid a premium to get him, I am sure they expected more from him than what he has done so far also.