fumbler:
(plural: ‘fumblers‘; pronunciation: the letter ‘u’ rhymes with the letter ‘u’ in “jumble”)

a fumbler, dropping the ball
a person who habitually makes mistakes because of lack of understanding or experience in what he/she does;
a bungler,

a fumbler, breaking plates
My new cook’s assistant is such a fumbler, breaking just seven plates, five cups and two bowls a day, that the cook has threatened me to get him a new assistant or accept his resignation.
There are some unlucky players who fumble with the ball just a couple of times and are called ‘fumblers’ and are kicked out of the team.
Of all the fumblers, the political fumblers are the worst, apparently telling lies and showing the fumble on their faces on camera and embarrassing their Parties in public.
In the present day political scenario in the US, President Obama’s opponents call him ‘fumbler-in-chief’ and his staff ‘team of fumblers’.
