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The main verb is 'is'. The subject is 'All he does'. It has a subject and a verb of its own. The subject is 'he' and its verb 'does' is emphatic. It's inserted for emphasis.
Main verb: All he doesis play soccer.
Take out 'does' and it's replaced by 'play',
Main verb: All he plays issoccer.
Switch the words around,
Main verb:Socceris all he plays. Main verb:Socceris all he does play.