Prediction & Reaction
Okay, people, break time for an important message for you theory crazy folks.
The average human reaction time to a single visual stimuli is -- frames, give or take a few. As a gamer, it is likely you will have enhanced reaction times, probably closer to -- or -- frames for a single visual stimuli.
BUT!
When you add multiple possible options, the reaction time rockets up drastically- this is because instead of simply recognizing and reacting, you must recognize, process, and then proceed to react. You will be reacting around -- frames at this point. However since you won't recognize that you should be reacting until about -- frames in, you will be reacting closer to -- frames.
Now you are all probably thinking this is bull- you almost never react that slow, and can easily recognize and react to moves much faster then this. That is because you are predicting ahead. To be even halfway decent at this game, you must be prepared and ready to predict and react ahead of time; you essentially skip the processing and recognizing phases; you register a visual stimuli which indicates your opponent has acted, and you immediately act with whatever action would best counter his predicted attack. If he did something that you failed to predict and could counter your options, then he would beat you out.
Essentially, brawl between good players is a match of mental magnitude. While melee focused on physical prowess, brawl is a slower paced, more tactical game. You (assuming you are a regular brawl player) know the options of your opponents character in most given situations. You know the tools he has, and what you should do in response to most of them. For every situation you find yourself in, you process (ahead of time) what his options are, what his best options are, what patterns has he formed, and how to react accordingly to the option he is most likely to use. In every match, in countless scenarios, you weigh options and must predict his most likely course of action, and throw out your counter to it. To provide an example, take the simple childs game known as rock, paper, scissors. You and your opponent are limited to three options, equally valid, and each dominates one other, and is dominated by another. Rock beats scissors but loses to paper. Scissors beat paper but lose to rock. Paper beats rock but loses to scissors. In order to win, you must predict what your opponent will throw and react by throwing what will beat his option.
However rock, paper, scissors is a simple childs game and lacks the depth of brawl- you have multitudes more options, not all of them are equal and serve different purposes, and depending on the situation there are always options superior to others. It is these options which are most often used, and thus you predict them using that and use an option that counters it- but if he predicts your prediction and counter, he can use an option, which, in the first scenario would be lesser, but now counters your prediction. Thus, the complex game of prediction in brawl unfolds.
The main purpose of this post however, was to inform people, and teach those who rely a bit too much on theory craft. While it is simple to look at a scenario and to already decide who has the superior option, and thus proclaim that character to win the scenario, theory craft fails to take into account prediction, reaction, and the intriguing sort of counter system that forms. For example, if you shield D3's Ftilt, you can punish him during its rather lengthy endlag. However what if he predicts your shield, and grabs instead? On the other hand you most likely predicted not ftilt, but his grab, as it is one of D3's best options on the ground, and thus you spot dodge and punished him. But since he knows that you know his best option is to grab, he chooses a lesser option and charges his D smash and hits you out of spotdodge. You see, in scenarios like this, that it isn't so simply clear cut and dried "x option>y option, so x character wins." Prediction and reaction are a huge part of this game, and people need to take it more into account.
And of course, the most popular and widespread of theory crafting, just power shield it. I will not deny that power shielding is an excellent tool in many situations and is a great skill to master; however it cannot be considered an end all be all. It is simply another option, and one that can be predicted and countered, just like most others. Power shielding has tight timing, and you cannot power shield on reaction- you can power shield on prediction, which is an entirely different matter. People need to understand the difference between the two- if you predict something, you weighed the odds and made an educated guess as to what they would do; if you react to something, you know what they have done, as it has been done- prediction is trying to see what your opponent will do next, reaction is seeing what your opponent has done. Both important, both needed to play brawl, but both distinct separate entities and should be treated as such.
EDIT