The candidate speaks smoothly without much effort. The linking words are used naturally and in the right places. He doesn’t cover the whole subject in his answers.
His vocabulary is appropriate but not sophisticated and doesn’t show variations, the language is fluent but relatively simple.
He uses some idioms and sometimes dose that inappropriately. The control of grammar is good, the mistakes are rare. His pronunciation is good and the accent doesn’t get in the way.
Many of them need to be very strong vocabulary, wonderful grammar, very unique ideas and very very fluent. Many of them can’t have all of these skills together, get something but not all of them. That’s the problem.