It's when your framerate drops below 60 that you see tearing.
To use vsync, your framerate should never fall below the 60 fps rate.
To vsync Crysis 3 you'd need a killer rig, with average frames around 80-90 fps and minimums sixtyish...
NVidia's Adaptive VSync monitors things, enabling vsync when your framerate is high enough (over 60) but disabling vsync if your rate falls below.
During that brief period, if there is a lot of action on screen or whatever, you may see tearing.
Most typical gamers have no business enabling vsync, because their rigs are too slow and their settings far too high...
Also, testing sites (including Tommy's) seem quite happy with framerates that are too low and details that are set too high, so following their example will not get you a good high framerate and vsync enabled!