Suppose some twist led to Subotai being recruited by the Jurchens before Genghis Khan did, and promoted to something like field marshal early on as the Mongol-Jurchen War escalated. Could Subotai's generalship lead the Jurchens to victory over Genghis Khan's army in pitched battles?
Without Genghis Khan Subotai would have been one more deadbeat in the Mongolian steppe.
Genghis Khan created the army, created the unity of "people of the long will" and he chose a smart brave guy and used to give him part of his army to follow his orders.
Genghis Khan taught Subotai everything, he gave him everything, without Genghis Khan Subotai would have been nothing. Like many a brave general whom genius of Genghis Khan saw and pulled out of obscurity.
Actually generalship of Subotai is somewhat overrated. For example during the famous first Western campaign he shared command with
Jebe and Subutai just happened to be a lucky one to outlive his partner and reap all the fame.
Subotai is more known among Europeans because he scared them shitless during final Western campaign.
Genghis Khan was very wise as he had a bunch of generals at his disposal and he left them as a legacy to his sons and grandsons.
None of the generals was indispensable.
The political, managerial and military talent of Genghis Khan was irreplaceable.