Giro D'Italia is the model and is indicative of the bend and the drop. Giros had more of a curve to the shoulder the Campione Del Mondo has a more square shoulder and the Criterium as an even great curve than the Giro and looks closer to the pista bar (in fact it would even be used in place of pista if one wanted a shallower drop. The curve starts earlier thus opening up the drop position. Criteriums are short and fast so rider spend more time in the drops and thus the reason for the early curve thus more or less eliminating the "rest position" on the curve.

Explanation 1 seems the simplest and most likely. That the stamp is not as deep is not surprising. There is less material there than when the sleeve was added. Steel stamped bars also had very shallow stampings.