As [deadrat][1] says, without more context it's hard to comment clearly.

Nonetheless, your first version sounds wrong in part because it's ambiguous. The first four words are a principal clause by themselves, but an ungrammatical one (<i>concern</i> is a noun and something acting as an adjective is needed &mdash; <i>concerned</i>, perhaps). Thus the first four words misdirect the reader to expect a different construction than you go on to deliver.

The focus of your thought in the sentence is <i>he</i>, not <i>they</i>. So you confuse things by starting as you do. I would use the grammar to reinforce the thought by making the same point but beginning the sentence with <i>he</i>.


  [1]: http://english.stackexchange.com/users/125330/deadrat