BBK3.. i WAS talking about the "load" or counter rotation phase... what is wrong with counter rotation in what you deem the "load" phase?
I teach my players to NOT load to the backside and then swing to the front side, but to counter rotate shoulders (slightly) and then when they want to swing, explode with hips first -creating a degree of torque in body (angle of open hips in relation to counter rotated shoulders) - and have muscles that act on hips swing bat.. effortless power.
If you are having problem with kids getting "hands too far behind shoulder and then extending arms to get swing started" then you have another problem... one, teach the kids that arms/hands do not start swing, two, teach them how to properly keep thier hands inside the baseball.... alot of people tell players "keep your hands inside"... but don't teach them how/why, etc.. in same breath you usually hear coach say " go get that pitch " - which are opposite comments...
I agree if they "extend arms" they typically lose bat speed, but you said " they HAVE to extend arms" - and to me no they don't HAVE to, if they are taught properly...
SANDMAN- if you are seeing nice, compact, powerful swings with a good swing plane while they are hitting off tee, but NOT in games... then it is not muscle memory yet... it takes an individual 1,000 - 2,000 repetitions for something to happen without having to think about it... make tee work a daily priority for a couple of weeks (100 swings per day?) and you should start seeing it carry over... JMO though....