There is way more too it than many fans think. It's largely a tactical/analytical role, the individual needs to be able to look at how the opposition approaches defensive/attacking setups in set piece situations and work out routines to break through or protect against them, and you need multiple routines. That's before you even start talking about throw ins. It's a job for a bit of a tactics nerd really. Just because you might have scored a few free kicks as a player doesn't make you a good set piece coach, hence someone like Baines is not the answer imo, it needs to be a proper person.