Last night was the first preseason NFL game between the Bears and the Ravens. Today was the first flurry of complaints about the new helmet rule in practice. Sometimes complaining about the rules in sports is just a separate sport. The Helmet Rule's Debut Was Really Messy - Deadspin; New Helmet Rule Could Make NFL Unrecognizable - Bleacher Report vs. Why the NFL's helmet rule won't be game-altering as feared - ESPN.

The new rule was established in March, and is intended to protect players. FACT SHEET - USE OF THE HELMET - NFL.
it is a foul if a player lowers his head to initiate and make contact with his helmet against an opponent. Contact does not have to be to an opponent's head or neck area – lowering the head and initiating contact to an opponent's torso, hips, and lower body, is also a foul. Violations of the rule will be easier to see and officiate when they occur in open space – as opposed to close line play – but this rule applies anywhere on the field at any time.​

Penalties for Violation: Loss of 15 yards. If the foul is by the defense, it is also an automatic first down. The player may also be ejected. Ejection standards:

Player lowers his helmet to establish a linear body posture prior to initiating and making contact with the helmet
Unobstructed path to his opponent
Contact clearly avoidable and player delivering the blow had other options

Although I didn't watch the game, I have followed the coverage and watched the clips of the three particular fouls in question. In each case, frankly, a foul would have been called under the old rules, as I see it. In all three cases the tackler was "leading with the helmet", deliberately initiating contact with the crown of the helmet. In the first two, helmet-to-helmet contact was the obvious result (Due to the severe nature of the injuries that can occur as a result of this type of hit, helmet to helmet hits are penalties in the NFL, whether incidental or deliberate.). In the third, a call of "spearing" (a tackling technique in which a player makes initial contact with the crown of their helmet by using their body as a spear, illegal since 1976) would have been appropriate.
A well reasoned argument is like a diamond: impervious to corruption and crystal clear - and infinitely rarer.

Here, as elsewhere, people are outraged at what feels like a rigged game -- an economy that won't respond, a democracy that won't listen, and a financial sector that holds all the cards. - Robert Reich