How the Date field is sent to the server has nothing with the format that the DatePicker format. The DatePicker widget helps you to create a control that will allow the user to update the underlying Date field from your viewmodel. The viewmodel is not aware what is the format of the widget(s) bound to its fields.
Thus said you need to configure how the dataSource sends the Date field to the server, by default it is using ToString() (this is why you see formats such as "Wed May 07 2014 00:00:00 GMT+0200 (Central European Daylight Time)"
To control how the datasource sends the different fieds to the server you should use the parameterMap
function of the transport, you can 'prepare' the format that your server side technology (MVC in your case) expects. On a side note you can use the kendo format
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