The Terrible T is an increasingly common and extremely problematic movement pattern and type of Timing problem in baseball pitchers.
The Terrible T is characterized by a pitching arm that is FLAT and not UP into and/or at front Heel Plant as well as a Glove Side that is also flat.
The Terrible T is often, but not always, accompanied by the Tommy John Twist.
The name is a riff on a movement pattern called the Power T.
By definition, the Terrible T is a form and cause of Flat Arm Syndrome.