thats how i think most of you are throwing the left hook
the left hook generates power from the rotational momentum of the hips transferring the momentum that it generates through the arm and into the fist. there are two ways that you can rotate the hips to transfer the momentum it generates into a left hook in boxing. you can initiate the rotational momentum of the hips by introducing a turning force to it which you can create by pushing with the left side of the hip or by pulling with the right side of the hip. the right side of the hip has the greatest distance from the left hook which means that using it to generate rotational momentum can produce more torque for a left hook than the left side of the hip can. pulling with the right side of the hip maximizes torque which you are going to experience as a whipping feeling when you are throwing the left hook vs a pushing feeling when you are throwing the left hook. there are some interesting physics behind this but i won't talk about it here. you have to understand how torque works in different sports when you are swinging a bat or throwing something however most boxers are never taught about how torque works or know what torque is.
when you have generated rotational momentum of the hips you have to then transfer it into your arm. the rotational momentum of the hips is what causes the arm to start moving. the arm does not start moving on its own. therefore the arm actually needs to be behind the hips as it rotates. the rotational momentum of the hips pulls the arm and is what adds whip to your left hook. the arm has to be behind the hips as its rotating to create whip and an arm that is moving at the same time with the rotational momentum of the hips and not behind the rotational momentum of the hips, and therefore being pulled by it, won't whip.
nonito donaire generates rotational momentum of the hips, pulling the arm, creating whip
most fighters instinctively drag the arm back and out to cause the arm to be behind the hips as the hips are rotating to add whip. most trainers think this is some kind of error and constantly try to fix it. they have to constantly try to fix it because fighters are going to constantly try to do it. they do it because they are instinctively trying to add whip. when a trainer succeeds in supposedly fixing this he has successfully created an arm puncher.
you actually have to drag the arm back and out when you throw a left hook when you are fighting in a squared up stance or your left hook will not have any circular range on it. a long time ago fighters fought out of a very sideways stance. out of that stance the lead arm, the arm that throws the left hook, is already behind the hip, and therefore the fighters that used to fight out of that stance, fighters like jimmy mclarnin and mickey walker, don't have to drag the arm back and out to create whip when they throw the left hook. felix trinidad fights in a squared up stance and has to drag the arm back and out to throw the left hook to get it moving behind his hip. this is the way he has to create whip fighting from that squared up stance.
you can know that the rotational momentum of the hips has transferred into the arm because you are going to start feeling the arm being yanked on very hard as the hips rotate. the arm is now going to start moving with a lot of force. as the arm starts being pulled by the rotational momentum of the hips finish the movement by aggressively turning the arm into a hook and powering it through. the circular range of the left hook is going to vary on how far from you or how near to you what you are trying to hit is. you can connect with the palm down or with the palm facing you however i recommend connecting with the palm facing you because connecting with the palm down has a tendency to skim.
i didn't talk about things like foot placement because this is going to vary from fighter to fighter depending on the stance that fighter is fighting in. however whats constant is that body weight is always going to end over the right leg when you finish. fighters like tyson and frazier shift a majority percentage of their body weight over their left leg loading the left hook with body weight. the transfer of their body weight starting over the left leg and shifting and finishing over the right leg is what creates their punching power. that is to say what they are actually hitting you with is their body weight as it is being expressed by the transferring of it from the left leg to the right leg. this is why they had really powerful left hooks.