Physical size is a significant factor in combative ability. A larger individual possesses greater weight and, often, greater strength. Obviously, someone who cannot efficiently handle his own weight is hampered by his size, but so far as size increases power, it is certainly advantageous.
If there were a martial arts conditioning method that could make you physically taller and larger, you can bet it would be a popular system. Nothing can make you taller, but training can make you larger in terms of muscular development.
Muscular strength is an asset as long as it does not restrict movement. If you are muscle bound, you will be too slow and stiff to reach the opponent.
This also applies to people who are too tall. There is a point where height is going to be disproportionate to the strength one can develop. A stocky individual will be stronger than a lanky one of the same weight because the lanky person’s muscular power is diffused by poor leverage in the limbs. Tall people also tend to have some joint instability, resulting from rapid growth, so some explosive movements can be problematic.
Aside from these considerations, the larger individual’s greatest weakness is often inferior training. This is partly due to the fact that larger people feel less compelled to develop a high level of skill. Such a person relies mostly on his size to manhandle opponents and, in neglecting technique, does not make full use of his natural advantage. A large practitioner who trains diligently to develop true technique is very formidable. Yes, larger practitioners may find it more difficult to perform flips and acrobatics, but these things are not necessary in a fight.
You must also not allow your pursuit of skill to lead you into neglecting the obvious advantages of size and strength. There is a tendency to completely reject strength in an attempt to focus solely on technique.
Strength and technique must work synergistically. Technique is not the rejection of muscle power, but rather the most efficient means of applying that power. Technique channels power. They are to be used in conjunction. Do not develop the mentality that the use of strength and external power is sloppy and constitutes forcing a technique. You risk the unfortunate development where a supposedly highly trained person is overwhelmed and overpowered by an untrained opponent.
Pure stylists become so devoted to preserving the integrity of a technique that they abandon the common sense of instinctive fighters by denying the strength aspect. This can be seen when someone practices a hundred and one different types of blocks, but then falls victim to a simple looping haymaker. They forget how to cope with more brutish attacks.
Do not become so engrossed with the minutiae of what you are doing, that you fail to see the big picture. If you can force a technique and finish a fight, then do it. Things do not always work out beautifully in a live fight. If there is one ugly technique that works every time, there is no shame in using it. When it stops working, that is the time to employ more sophisticated tactics. Reach for the simplest tool first.