To quote that famous quote, 'power corrupts and absolute power....'
How does the membership know that the mod team are working in the interests of the site effectively across the spectrum of duties? We can all agree without a shadow of doubt that an excellent job is being done in regards to spammers, minors, fakers and thread removals in breech of ToS. But what about the actual community involvement, banning some of the biggest contributors whilst engaging rarely in threads (one or two notable exceptions). Do you even care about the site you're modding? (one Admin at least excluded, clearly they do, but everyone else?)
The criticism might seem unfair, but it exists because of one seemingly over the top response to an infraction to another, and the mod team stay silent, and for why? If there was confidence that the most appropriate course of action was taken then we should surely see a thorough explanation to put down critics. The absence of this openess/lack of clarity does yourselves no favours.
Are you perhaps concerned that your reasoning would'nt wash and therefore your credibility as competent MODERATORS would be harmed? Don't worry, it clearly already is to many, so you got nothing to lose.
I recommend you have a social group made up of longtime, high post count members who can be privvy to the full details following a high profile members banning, and then to be allowed a vote on it themselves. This way, if the moderators actions are felt too excessive for whatever infraction, it allows a banned member not to have to approach you having to apologise for something which was treated too harshly to begin with and furthermore adds some membership protection for those members who might have just ruffled the majority of the mods feathers, clearly not helpful in reaching an impartial action to be taken.