Fleet tactics do matter in Sins. Here's an example:
Pirate bases are ridiculously hard to take. Since raiding parties spawn and return to the base after completing the raid, by the time you're actually in a position to take the system they've got a hundred of everything and the place is just a black hole. Unfortunately, you have to destroy the pirate base in order to stop the attacks, and pirates are a huge drain on your economy late game.
Last night I was playing TEC versus an easy Advent (it was my first real game) on a small map, but I quickly realized that my true enemy was not the Advent, but in fact the sprawling Pirate Empire. So far I'd manage to keep them occupied attacking the Advent's planets, but my bounty was fast approaching five digits and I was starting to get low on credits. Clearly, the Pirate Empire needed to go.
The Pirate Base was nestled between the Sun and an asteroid field I'd recently taken from the Advent, where most of my ships were stationed. My fleet consisted mainly of Kodiaks and LRM Frigates, with a level 8 Akkan (ECS Akkan) for a flagship, a level 3 Marza (ECS Marza) for artillery support, a level 2 Soza (ECS Solonis) for fighter support, and 5 Kols of varying levels for blowing things up. My initial attempts to take the system were disastrous, and I spent a small fortune rebuilding most of the capital ships I'd lost. The second attack seemed to go alright at first, but it quickly went south after the two large swarms of Corsairs reached my battle line. Then, I devised a plan:
The capital ships and Kodiaks - henceforth referred to as First Fleet - would be start their run in the asteroid field, while the LRM frigates and a small squad of Krosevs - henceforth referred to as Second Fleet - would circle around and hide in the sun's gravity well until I was ready to go. I would start the attack by jumping First Fleet into the system, where they would start blowing things up and draw the attention of the two huge swarms. Once the pirates closed on First Fleet, Second Fleet would jump in, using the solar radiation to cover their approach. The Krosevs would then attack the base proper, with supporting fire from my Novalith Cannon, while the LRM frigates would use the range advantage to blast the enemy with missiles while they were tied up fighting First Fleet.
Phase One went smoothly, with the Novalith shot hitting the Pirate Base very quickly after First Fleet's arrival, though one of the less experienced Kols was forced to retreat. Second Fleet's arrival was somewhat poorly time, as I rather stupidly ordered them to jump in as a group, but they got the range advantage they needed. I made another stupid mistake by order them to engage cluster missiles prematurely, but the plan seemed to be working well enough.
Very quickly, the pirates reacted by splitting their massive fleet in half, with the majority of their ships moving to engage the LRM Frigates. After they got within combat range, I ordered the LRM Frigates to retreat to the far side of the gravity well, splitting the enemy force in two - the bulk of it chasing the LRM Frigates, while a few ships stayed behind to shoot up Second Fleet.
Unfortunately, the pirates managed to force Second Fleet into a tight spot, up against the edge of the gravity well near the phase lane leading into Advent space. Not wanting to lose so many LRM Frigates - the Krosevs had all been chewed up by the defense cannons by this point - I had the Akkan engage Armistice and ordered Second Fleet to circle clockwise around the edge of the gravity well, about halfway toward First Fleet (and into the jump arc of the phase lane back to the asteroid field).
At this point, First Fleet was having trouble. Another of the new Kols had been forced to retreat, the ECS Kol (level 6) was taking heavy damage and the Solonis had already sustained heavy damage and was currently hanging around at the edge of the gravity well, still providing fire support but with the option to get out in a hurry if the Corsairs took a liking to it. Kodiak casualties so far were light (I think I lost 2 out of 22 in total), but I was definitely considering using the Armistice to pull out and try again with a bigger fleet, but fortunately for me, the Corsairs still fighting First Fleet decided they would be much more productive assisting with rounding up Second Fleet.
That left only three defense cannons between First Fleet and the Base. Shortly afterwards, there were no defense cannons between First Fleet and the Base, and they opened up. The Novalith had reached cooldown by this point, so they got another long-range artillery shot, and in the space of a few minutes the Base finished exploding.
There were still over a hundred Corsairs left in the gravity well, and they were all descending on my poor LRM Frigates, so I decided to call it a day. The Akkan engaged Armistice, and both First Fleet and Second Fleet hit the phase lane back to the asteroid field, leaving the once-mighty Pirate Empire broken and disorganized.
Yeah, fleet tactics matter.