He a young(,) energetic head coach.

That's problematic.

If the entire sentence is "He a young, energetic head coach."--then it's a sentence fragment, without a verb. It could read "He is a young, energetic head coach." There are many possibilities for the verb. It cold be "He was a . . .," or "He would have been a . . .," or "He tried to be a . . ." Whatever you use, you need a verb. Over the last few decades, the comma has fallen into desuetude--which means it is not used as much as it once was. Many contemporary writers in English would not use the comma.

However, if this is an intentional sentence fragment, an introductory clause, then you need the comma and some other punctuation. So, for example, it might read: "He--a young, energetic head coach--was well known for his heavy training schedule." The modern, lazy bones attitude toward commas might also dispense with a comma in that sentence.

No matter how you write it, though you need a verb.

Given Ms Tan's excellent English, I'm pretty sure we can say this was a typo, Set.

Thanks, JTT.

You are right: it's a typo. However, my English is not excellent, but mediocre.

What is your view on the comma? Is it the same as Setanta's?

He is a young(,) energetic head coach.

I might include the comma, Ms Tan, because of years of "that's how you do it. Punctuation varies dramatically depending on where it's used and it is changing rapidly. The comma in, that's the traditional way but I would do it how I think it is being said.

That said, in an academic setting I'd likely follow the pack.

Thanks, JTT.

My pleasure, Ms Tan.

Thanks, Setanta.

You're welcome.