General principle: short sentences convey speed, long and meandering sentences will give the reader a sense of drawn out time. A pitfall many writers fall into is over describing their action scenes, which makes them seem oddly sluggish and dull.

The revision shown in the article to "A Bad Uncle lifted Captain Samson over his head and hurled her over the edge of the catwalk," is an example of this problem. The reader knows how you throw someone, they don't need an explanation.

"The Bad Uncle hurled Captain Samson over the edge." (Presumably the reader knows they are on a catwalk, too, so "the catwalk" is unnecessary.)

If it is really important to convey that the Bad Uncle is very strong you could do "The Bad Uncle hurled Captain Samson over his head, off the catwalk," or something similar.

Edit: Also, the article discourages adverbs, but doesn't mention that adjectives are similarly bad. Most adjectives can be better conveyed through an action or specific detail. Don't say "she was nice", but do show her helping a lost child.