Imagine seeing this sentence staring up at you from the pages of your first draft:
The candidate made bold predictions that have not been lived up to.
Clearly this sentence hurts the eyes and ears, but why? What's wrong with it?
1) It ends in a preposition (lived up to),
2) It uses passive voice (been lived), and
3) It contains an unnecessary compound verb (have... lived).
A trifecta of bad writing! Let's think about some possible ways we can repair the damage:
The candidate made bold predictions which he did not live up to.
This version is improved, thanks to the elimination the both the passive voice and the compound verb. However, it still doesn't read well--and it still ends in a preposition.
Let's try another version:
The candidate made bold predictions up to which he did not live.
This is grammatically correct--in the same way this is something up with which I shall not put is grammatically correct. Only a tool or an Englishman would write something like this.
The candidate did not live up to his bold predictions.
This works. It's simple, direct, and it breaks no grammatical rules. But I think we can do better.
The candidate made bold predictions, yet failed to live up to them.
The first half of the sentence sets up an arc of expectation, while the second half flattens it with palpable condescension. This sentence is less simple, but much more savage. Which is why it's the best version of all.