Being shorter can hurt, but only because it limits what you can really say. If I spend 2000 words beating you up and your entire promo is 750, you can't match me in most cases.

Now, that's not to say that writing super long shit is the way to go. It's not needed in most cases, but there are definitely some who will have that advantage. One way to maybe rectify that is to combine promos to double the size - instead of having 6, just have 3. Kind of the opposite advice I usually give the long-winded types (general consensus is that 2000-3000 words is about as big as you want to go.)

For you I think the easiest way to beef it all up is with some more scene and background. Your stuff is mostly dialogue, which is fine, but it could use some meat in the scenery department to give me a clear iea of what this guy's life is.

I liked the way he went right after his opponent and pissed on his parents' graves, that's some good heel shit. Gives a clear idea of the type of person he is.

Overall, I'd say you're above average. You'll get better and it will get easier once you settle in and you know the dynamic and the characters.