In the first period of Saturday's 2-1 Flyers win over the Senators, Lundin carried the puck into the zone before quickly passing off to a teammate. Zolnierczyk came directly off the bench and across the ice and literally launched himself off the ice and shoulder first into the head of Lundin, who left the game with what was later stated as a concussion from the hit.
Here's the video from Brenden Shanahan and the NHL Department of Player Safety on the hit:
Shanahan specifically points out that Lundin braced himself for a hit in an area where players need to be aware they could be targeted, but in no way should he have been prepared for a hit of that magnitude. It's also made clear that Zolnierczyk had launched himself more than a few inches off the ice prior to the hit, instead of his skates coming off the ice as a result of the hit.
When the NHL talks about cutting down on dangerous hits, this is exactly the sort of targeted collisions that is being discussed. There's no need for Zolnierczyk to get that high on Lundin, although it certainly seems as if the intent was to make a hard and legal open-ice hit -- and once again, we see that the result (concussion) had as much to do with the suspension as the hit itself.
Fair or not, that's how it works now.