As your BBM might well be deep into opposition territory when attacking, you could run the risk of being caught on the break if you lose possession. The opposite scenario is that he is too far back when you are defending, and hence he needs somebody ahead of him to instigate an attack.
Hence it would be a good idea to have his midfield partner set to a "support" duty, whether he be a playmaking midfielder or otherwise. His role depends on your playing style and also your formation. Are you using a DM or AM, attacking or defensive strategy?