The phrase "are very proficient" is correct and usable in written English.
You can use it to describe someone's high level of skill or competence in a particular area or task.
Example: "The team members are very proficient in their respective fields, which contributes to the overall success of the project."
Alternatives: "are highly skilled" or "are extremely capable."
"Let's say you are very proficient with numbers, quantitative work and with using the Excel program," Mr. Evans said.
The British are very proficient at eliminating veterinary diseases by killing and incinerating animals, officials said, noting that more than 160,000 birds were swiftly killed to contain the British outbreak.
Some of those lawmakers are "very proficient" with firearms, Massie said.
Lifeguards and surfers, of course, are very proficient swimmers and have experience swimming in surf conditions, so most of us shouldn't intentionally enter a rip current.
Narcissists of both the overt and covert types are very proficient at gaining the sympathy of their supplies and becoming the center of their world.
We, those out in the war, are intensely focused on something we're very proficient at.
You might not be surprised to learn that she is very proficient, too, at Japanese flower-arranging and dressmaking.
Gill said McClay, who was from the Barrow area, had worked at the wildlife park for a number of years and was "very proficient" in her work with big cats.
I can't speak for anyone else's pantomime, but ours is all about positivity and looking at issues such as bullying, and making it clear that just because a child is not very proficient in one thing, it does not mean that they can't be very proficient in another.
"The CoS is very proficient at the internet now, but I believe that was only responding to very successful anti-Scientology sites on the web in the early 90s". One of the Church's US lawyers tried to get news servers to drop the alt.religion.scientology newsgroup, which not only failed, but created an outcry online.
