Teleport to Portbattle

[Conte D. Catellani]

maybe I'm wrong but the tp work only in one direction so seem you have to stay anyway ready to screen if something goes wrong and help the attackers coming back 

[Sir Lancelot Holland]

Generally speaking, the defender will usually hold the advantage, they already hold the area so defence is usually area denial, that is what screening fleets are for, to deny the attacking PB access to the area.  This is why any attacking fleet should, of necessity, be two to three times larger than the defending force in order to force entry. TP into a PB removes that defensive advantage and gives it to the attacking fleet, especially where the attacking ships are of better quality and with better skilled players.

Now if an inferior defensive fleet can hold off a superior attacking fleet then they have done well, if the attacking screening fleets tie down the defensive  screen then the attacking PB fleet will get in and very likely win the PB as happened frequently in the late Anglo-Swedish war, The few PB's GB did win were due to a solid defence, utilising all of the defensive advantages, and, where the Swedish PB fleets were denied entry, or, had limited entry to the PB area.

Take away the defensive advantages and the better quality, better skilled side will usually win, barring errors or misfortune. The only real effect TP into battle will have will be that eventually the defending side will say there is no point in defending at all, for the attacking side there is no battle, so where is their content, sailing in and winning by default gives no one any satisfaction,, and, defeats the object of port battles completely.