stumble, blunder

The word 'bumbling' is an action; the act of being clumsy or awkward, a verbal noun (gerund). An act can't possess something.

I will not have you, in one night, besmirching that name by behaving like a babbling, bumbling band of baboons! - Professor McGonagall (Harry Potter and the Goblet of Fire)

Cake Boss - 2009 Beer Buttercups and Bumbling 5-7 was released on:

USA: 18 June 2012

The diplomat was a bumbling fool; many wondered how he achieved such a position.