Khan just has no ring IQ. He's a moron in the ring. Combine that with his weak chin and the problem compounds itself. Garcia would KO Khan 9/10 times. Willie Limond is a national level boxer. He's a decent wee fighter and he's from the area I grew up in. In his 42 fight career he has 10 wins by way of KO - only one of which is a 10 count KO. Go to YouTube and see how long the count Khan got was in the Limond fight. It's a 13 second count - one of the worst I've ever seen. This would be the equivalent of getting sparked out and being down for over 10 seconds against someone like Paulie Malignaggi - pillow fists. Khan just has no chin.
Well its a combination of both actually. Khan stood in the pocket whilst leaving himself totally exposed for the first time, he himself said he got careless as he found it far too easy to hit garcia, a clear lack of discipline. Had Khan not stayed in the pocket like the first 2 rounds he would have avoided that shot. Actually if he had threw a 1-2 he would have avoided that shot because his shoulder would have provided protection to his chin. Khan also made the exact same mistake vs prescott, throwing an uppercut in pocket which left him exposed to the left hook. After seeing him take that year out and going to basics with Virgil he has ironed out some major bad habits. He's carried on taking part in camps with virgil in between fights, so I expect an even wiser more patient and thoughtful khan vs Alexander. I also think Mayweather has made a mistake by not fighting Khan in May 2014 as he was still in transition phase.
I'd say Khan and Garcia is a lot like Froch and Groves. Groves will outbox Froch any day of the week but if Froch lands clean it's over.