yes and no....of course the elbow is elevated in a sense that it is not down on the body or even or in worst case below the hands...it should always end up above the hands at contact....
No - the elbow is not a teach....if the hands work right the elbow will do what it is supposed to do....have a lot of experience around here with lead elbow pull type teaching....it is not what I recommend....the elbow wings up and out leaving the hitter trying to salvage some swings as they are pulling off...
Like I have been saying - if the bottom hand is rolling correctly - the barrel can be turned/thrown into contact with much more velocity because the bottom hand can decelerate correctly allowing the top hand to throw past and provide the pop in the swing....I might use the bottom hand as emphasis, but obviously the front forearm is rolling as well and this allows the front arm to lengthen (extension) or pull in as need be....if the bottom hand is hammering in plane and the forearm is not allowed to roll (trying to give you another visual) the elbow hinge will bottom out sooner and force the hitter to pull off with either the elbow, shoulder or both....the wrist can hammer only so far if the forearm isnt allowed to supinate (roll)...
The reason this needs to be taught is because too many hitters are taught to either lead pull with the elbow, or are taught flat hands at contact (see pizza toss drill) or are taught to hammer with the bottom hand....
This is a snip-it from an article called "Big Hitters, Same Hitting Drills"
The scientific reasoning behind lead-arm extension is that the amount of leverage you can achieve. In the baseball swing, your front arm is the longer lever and will therefore provide more leverage and power. And that is my I warn my students not to roll their wrist over prematurely because it will keep them from maintaining the flat swing that allows for extension.