OK...back from my public holiday (go the Diggers!), but probabaly not for too long coz the office is half empty and therefore its been declared a boozy lunch at the pub day.
For my first hypothesis I'm going to state that strategy in SE in no way mimics strategy in real life. This is largely due to the fact the that SE is a computer game and has limits, reducing possible actions to just a handful, with known bounds on anything from technology to methods of warfare.
Now getting back to offensive/defensive bonuses and importance to any success.
First I'de like to state there are two forms of defeat in SE4.
1. An early sneak attack. Whether its backstabbing an ally (rare coz I rarely see alliances break), stealth armour and planetry napalm or swarming in on an unsuspecting empire coz the player believes everyone likes to trade colonisation tech before they fight. Nothing really matters in either of these cases, the defender dies (either quickly or they flop around like a dying fish for a while).
2. A more conventional defeat. These are usually broken into two battles. The first battle is where the invader busts through the defence of one side, usually the defender's older ships that have been sitting on a warp point. The second battle is where the defender does a mad scramble of all available ships and throws them into a Last ditch defence.
I've seen the second scenario replayed a dozen or so times. More often than not the battles are extremely lopsided, with one side been completely wiped and the other suffering few losses. The defender suffers a demoralising defeat, the invader an almost embarrasing victory. The ships can even appear similiar in technology.
There are really only 2 factors in these battle that lead to the defeat.
1. Ship placement. (My gripe with SE combat at the moment). Besides the case where one fleet come through the warp point (I know where that fleet ends up) I have no idea why SE places the ships where it does. I've seen battles where one side forms a neat little queue to the killing zone, when both sides are completely scattered over the map or in a recent battle between 70 attacking dreadnaught against me (50 battleships) and my ally (30 base ships) I ended up packed tightly in one corner, my ally in the opposite corner and the attacking dreadnaughts scattered around where I was, including some ships that were completely surrounded by my ships.
2. One side only hits 1 in 6 shots, the other side hits pretty much every time.
Although there is nothing you can do about 1 (or I think there is anyway), number 2 is all about your offensive/defensive bonuses.
Success in the game does NOT depend on technological advantage, its depends on an advantage in the correct technologies. You can concede a disadvatange in shields, ship size, weapons, construction, resource production as long as you are superior in offence/defence.
Well thats my scientific explanation of strategy in SE4. Obviously I think about it too much but I must say that about 1 in 10 turns I play are after coming back from the pub. So maybe Belisarius is right..its about 90% science and 10% art
Askan