Honestly, even with all that self confidence and ability, he was much more likely not to succeed! Here is NAM Rodger, a leading historian of the Royal Navy, on the subject:

The only tangible reward [for gallantry] was promotion...[t]he problem was that in a long war there were many examples of gallantry - and all the more of them as young officers realised that this was their only chance of promotion. The number of those it was just to reward bore no relation to the number it was possible to employ. The practice of advancing all the first lieutenants of the ships of the line which had fought in a fleet action, insituted in 1794, had a particularly devastating effect on the Commanders' list*.

In 1806 Wentworth had just been made commander in consequence of the action off San Domingo. In other words, he is one among many of those lieutenants advanced following a major fleet action. He was lucky to get a ship after he left Somersetshire, and he must have done something pretty spectacular while commanding it to have been promoted to Post Captain :-)