Yep. People cry "dive" way too easily. When you're already on the ragged edge of balance trying to move fast, even a small amount of force can make you completely lose your edge in a way that looks really stupid on replay, especially slow motion, but is a perfectly legitimate fall. Same with the Skjei controversy early in the game. He was twisted around four ways to Sunday and got torqued while he was already in a weird off kilter position. Very few players are going to be able to keep their feet in that scenario.
As for there being padding on the back of the leg, it's a thin soft layer that only really covers the calf rather than the hard plastic in front, and older generations of shinpads don't even have that, just elastic straps. And a lot of NHLers use the ratty old gear they feel comfortable in rather than the more modern stuff. If you whack the back of the leg, you'll feel it. More importantly, if that whack moves the leg enough to slip the skate forward, you very well may lose your footing. Slavin just isn't a guy who's going to dive, either. It's simply not in his DNA, and I think he's more than proven that over the years.