So,...AF lock is new eh? Wow..this AF tracking is new too eh? Wow..
That is a decent site to read through....until you see that Canon has been doing this stuff for many years..
Since I switched to Canon in 1996, I have had all my Canon camera bodies, with the exception of the 620 body,...(because it couldn't)..set up so that I could auto focus independently of the shutter button,...which is a LOT better than "focus and recompose".. The shutter release button releases the shutter, and controls the auto exposure locking function.. and with the high speed cameras, the AI servo auto focus mode has a slower frame rate while actively tracking a moving target..well,...if it is not tracking/follow focusing that target, even on AI servo mode, can fire off the frame rate at the same speed as the frame rate on "One Shot" mode..which basically means that it is focused on a still standing target.
Say like in baseball,...I anticipate the guy on first stealing second base.. I see the guy running there...since there is noting interesting about a picture of a guy running between bases, I will shift my attention to 2nd base,...and pre focus on the base it's self, and then wait for the action to develope, and then fire when ready, rather than trying to focus and compose because I have to have the af point on top of the point of action, and with bodies sliding, and dirt flying,..things can get confuseing out there.. I've had many many more "keepers" since I began using this method..
In addition to this,...on all Canon L lenses, and several non L lenses,...they feature "full time manual focusing" capability..and what that means is that no matter what focus mode you are using, you can still turn the manual focus ring, and be able to over-ride the camera's "brain"..this is especially helpful when shooting action where you have to track/follow focus on a specific target that has other things standing or running between you and that specific subject.......and since it is your goal to keep a close watch on that subject,...you have to think ahead of the camera's "brain",...because the camera may switch the AF tracking to one of those individuals running between you and that subject, and you have to (with skill)..follow through with manual focus..until you get the shots you need........example,...a wide reciever running across the field for a catch,...tight-ends are especially dificult because they are running around the line..and running backs,...the hand offs,...and the running through the line can be hecktic if you rely on only the camera's ability to think for you..
Another thing,...the super telephoto lenses have this,...and I really wish the 70-200L had this too.. "Auto focus Preset". The lens has this switch on the side on it.....say you are shooting on the side line of a soccer field..and you aren't moving around at the moment.. and you think that there may be an attempt at the goal box,....well,...the AF preset makes my life a whole lot easier...because all I have to do is get an accurate focus of the goal box,..or slightly in front of it,...and then pull that switch in to me, which marks that point of focus,...and then I can continue to focus all over the rest of the field, clicking off frames of this guy, and that guy,...and then I see someone in a scoreing position,...all I have to do is turn this gear like looking ring on the lens barrell, and it automatically goes right back to that specific setting, and all I have to do is wait for the action to develope,...rather than holding down the AF & shutter release button, and hoping that the path to the point of where I want to focus is clear so I can take a picture... usually by then, the action has already happened, and I've missed the shot...so,...Canon AF kicks ass!
BTW,.....they forgot to go into detail as to why so many professional sports shooters who use Nikon are having trouble with back-focus.. I happen to know a few.. Oh, and they are looking into switching to Canon as well now..