The following flaws are the most common among hitters.

. Arm Bar
... Hands Behind the Back Elbow
. Bat Drag  
... Fixing Bat Drag
. Chopping Down on the Ball
. Cutting the Swing Short
. Disconnection
. Dumping the Barrel
. Drifting
. Dropping the Hands
. Excessive Uppercut
... Slight Uppercut
. Fanning the Front Foot Open
. Lunging
. Stepping in the Bucket 

In addition to the Common Hitting Flaws, there are other hitting flaws that you tend to see in more advanced hitters. The ones I see the most often are...

• Leaky Hands
• Leaky Hips 
• True Loop

Other flaws that you see in advanced hitters include...

. Casting the Barrel   
... Arm-y, Top-Down Swing 
... Getting Long in the Back 
... Hitting from the Top
. Dominant Back Arm
... Derek Jeter's Dominant Back Arm
. Extension at the POC on Every Swing
. Jumping the Gun 
. Lack of a Delaying Mechanism
. Pulling the Hands...
. Not Loading
. Push Disconnection
. Reverse Running Start
. Soft Front Knee
. Stomping the Front Foot
. Stalling the Barrel
. Sway