Stick/pad hybrids
An interesting aspect of the gamepad evolution is the recurring return to prior metaphor. Although the stick and pad “paths” diverged from the beginning, several hybridization occurred over time. The two paths crossed several times over as shown by the examples depicted in this blogpost. The threaded hole in the center of the d-pad allows indeed to add a mini joystick which takes different shapes or color. Of course some are more carefully-crafted than others (the red mini-stick is a bit rough while the one above is more complex). 
Although I am not a great fan of the “evolutionist” metaphor, I find interesting to observe how certain features are chosen and integrated by designers.
