Excellent stuff Raymus. Thanks for articulating what many a top player intrinsically understands but till now has not been able to explain as clearly. I've been wrestling with the ideas of ranges, optimal offense and defense recently, in a bid to level up my Makoto and honestly I can't believe how long it's taking me to master these concepts.
It's definitely much more than just 'chiong' or 'turtle', ideas which are as uniquely Singaporean as parliamentary democracy (HAH). And I realize, after watching and playing with top players at EVO, that my gameplay was fundamentally flawed because I was brought up in an environment of black and white, where it was either attacking or well, not attacking.
I'm not saying everyone in Singapore thinks like this, but (and no offence to Kaiser, just using this as an example), but the following ideas epitomize the general mindset of Singaporean players, and they are dangerously simplistic and naive:
Agreed but not all have what it takes to be a chiongster which is why we sees turtles everywhere since they can't link/do combo well and doesn't have any good quick reflex during the matches.
And it's the same opposite,as many chiongsters seems to forget that there's an option called BLOCK and can't keep their calm while defending so we can't blame anyone when our opponent pohs and landed a ultra/dp.
Ps:I'm one chiongster with weak defense that always rush in even if opponent were left with 1health and me full.And sure kp when loses to turtles.
Anyway,I doubts "Running around with an life lead" will be a proud scene when it wins.
And thanks Raymus and others for reminding me to block whenever I'm on life lead but still keep rushing in arcades.
Offense does NOT just = rushing, chionging, pressing buttons, being able to do combos etc
and similarly
Defense does NOT just = blocking, turtling, backing off, not pressing buttons, not being able to do combos etc.
which I think is the crux of what Raymus is saying so I won't repeat his points.
Rushdown/Zoning are certain styles of play, which cater to different characters and preferences. HOWEVER rushdown and zoning are but mere ELEMENTS of both offense and defense.
Now I don't claim to be an expert on both, and honestly after much thought I feel that I am actually very weak in both departments. But after learning and experimenting with Makoto, whom I've learnt flat out demands an excellent knowledge of range and being able to balance offense and defense flawlessly, there are some things which I realize determine good offense and defense, things that I see many top players internalize, most decent Japanese/American players do, and unfortunately only a few Singaporeans actively pursue.
1) Good offense does not = being in your opponent's face all the time and pressing buttons, although that does happens as a result of good offense. Good offense definitely does not = doing damaging combos. On the contrary it is the creation of opportunity, the use of your understanding of your character's moveset, your opponent's moveset and your opponent's tendencies/habits to create situations for you to utilize said damaging combos or mixups.
2) Good offense is active as much as it is passive. This is where optimal ranges, and reading your opponent come into play. For example, using Makoto I know that I have a great poke - c.mp, which can be buffered into ex hayate, which leads to cornering the opponent AND the opportunity to lead into more mixups (because the risk reward is in Makoto's favor once the opponent is cornered), more damage, and ultimately, winning the round.
Good offense from me would mean proactively maintaining the range/distance (as Raymus mentioned) where c.mp will hit, where c.mp would beat my opponent's own buffer poke, and more importantly, where my opponent cannot punish my whiffed c.mp, should it not hit. I can either move forward, to encroach the space my opponent has in front of him, testing him with c.mp, or wait for HIM to enter my space. This is why often people walk back and forth across the screen, to fight for that optimal range where the limbs they stick out will trump the opponent's.
That means......I can actually walk back, 'turtle' AND still be considered maintaining good offense.

Yeah my mind was blown too.
On the flip side, walking back, backdashing and not challenging your opponent's wake up/space can be considered bad offense as well. Another example: Makoto's backdash is gdlk, and pretty much keeps her safe from any reversal uppercut. So I'm able to knockdown my opponent, and for fear of eating a reversal, I backdash. Some people may think, yeah this is good offense, me baiting out my opponent's moves etc and whatever. But I failed to consider that I was chasing a life lead, my opponent had less than 2 bars (uppercutting when you don't have meter to fadc is high level tho, real talk), and honestly, I had NO REASON to bait his reversal at all. That's fucking bad offense man. I'm Makoto, I should be either at the optimal c.mp range, or up in his face because i have an excellent s.mp with 7 active frames, a command grab and an axe kick to blow up escape attempts. SO WHY DID I BACKDASH?!?!?
Good offense is essentially making informed reads, knowing when your opponent's gonna reversal, and when should you press the advantage/back off. At the highest levels though, people KNOW what the best decision is, in that particular situation, hence they try to throw you off by doing something uncharacteristic, like said uppercutting without 2 bars. (Have you watched a Poongko match recently?) Hence something that is seen as 'wah cb luan poh eh', can be actually considered an amazing read, and that's why this game is so fluid and awesome.
3) Good Defense does not just = Good Blocking.
WTF?! YFOLJ!
Carrying on from the previous point, an uppercut from out of the blue, or 4 uppercuts in a row (ahem Daigo at EVO 2011) should not be dismissed as 'poh' immediately. I mean think about it logically - If the supposed 'best' decision in that situation is for me to block or delayed tech, and you know that I won't do an unsafe reversal because I don't have the meter to, and HENCE the smartest thing for YOU to do is to pressure me on my wake up....then won't the REAL best decision, all factors considered, be for me to let one 'random' ultra/dp rip?
This is a problem that intermediate players (i myself for one) and even good players face. They're too caught up in playing the game so elegantly, so frame perfect that they lose the element of surprise, both offensively and defensively. The fact that good player A is so good at crouch teching, and blocking, and won't reversal unless he has at least two bars actually might work AGAINST him. That's why getting good reads on your opponent is so important.
Good defense is in essence as much about mixups as good offense. What I've learnt, from observing top players, is that their defense is filled with as many variations/options as their offense, which leads me to conclude that Offense and Defense does not mean just attacking/blocking!
Defensively, you have backdash, reversal, crouch tech, delayed crouch tech, standing tech, focus back dash, focus front dash, wake up jab etc etc etc. You are just about as dead if you are predictable with your defense, as you are predictable with your offense. Know your defensive options (NOT JUST BLOCKING AND TECHING), calibrate what works best based on what your opponent has, can do, and his tendencies, and you're more likely to emerge unscathed during pressure.
Sorry for spamming, but only after seeing the game played at the highest level do I realize how inept I actually am, and how shallow my gameplay is. There's so much more, beyond the above concepts mentioned, that constitutes high level SF. If you find what I've said obvious or second nature, then more power to you. But I hope that I've helped highlight some things that we might have otherwise overlooked. Thanks Raymus for starting the discussion, once again and yeah,
let's step our shit up together.