Fun regular seasons are what the Bruins do best. Been that way practically forever. Playoffs are a different beast.
Really with exercises like this it depends what your expectations are. If you expect Cups and no less you're going to grade harsher when they don't materialize as opposed to someone who is looking more for consistent high performance, which the Bruins have undeniably had in spades.
I don't want to get into the nitty gritty of the grades (although the D for draft and develop and the overall C+ are absurdly harsh), rather I'd make the observation that if you asked me whether I thought Boston's front office overall did a good job I'd say an easy 'yes', but if the question was 'do I think the current management will win a Cup', my answer is 'unlikely'. In simple terms, for all our management's competence, you need a little bit of magic and/or some sheer luck to jag a Cup, and the current crew just don't seem to have either.
I also think you have to separate management from ownership, and acknowledge that the hands of the former are partially tied by the latter. This is old ground but the Jacobs have made it very clear that they expect the Bruins to compete just about every year because it ensures the ongoing profitability of the franchise. Any sort of serious rebuild is off the table, the amount of risk the front office can take on has a ceiling. There is a certain way the team needs to be run, and really it's changed little in 40 years.
In that sense to be fair to management you have to evaluate them in light of those limitations. And once you factor that in I think that, for me at least, whatever gripes I have about our front office, and there are a few, it's the owners that I have more of a problem with while fully conceding that, barring some cataclysmic event, they aren't going to change.