Thank you for your answer maxwell.
Maybe more info are suitable: in 2 weeks I managed to gain 175k points, climbing the top 20, I've already read all the info and tutorials possible, but I'm still at a deadpoint.
You are right when you say I leveled up renegades causing more power than my fleet can handle.
You also say "Remember the highest leveled ship yard on any of your planets counts for calculating the renegates power, not a low leveld ship yard on the attacking fleets planet", but this doesnt match with the info I have: renegades unit numbers depends on the numbers of popolation of ships I send against them. No Shipyard involved, nor population of the planet that send the attack, if I'm not wrong.
Now I'm stacked with my poor level 4 explorers and level 1 cruisers against a lot of level 6 pirates, that's insane. I'm already giving up to gain any improvements points.