Someone who is articulate and able to sound impressive by theories or speech but do not have sufficient experience in real world applications. The word/idiom that I am looking for is without negative connotation. Phrases like "is all talk" and "look good on paper" have a sarcastic tone which I want to avoid.
The scenario I have in mind is someone who has graduated from a course that is relatively new to the market. There isn't a great demand in the market for such expertise yet. The person can only accumulate knowledge by research. They are able to convey impressively by theory. However, they do not have enough experience in real world applications yet.