I still occasionally get asked why a company needs project managers. It's a better question than many people realise as a lot of your staff probably know what they should be doing, and are busy getting on with it without any project management required.
We can find a pretty good example of the need for a project manager by looking at the sales process. Sales is hard work and certainly not something I claim to be any good at. The product being sold is frequently not perfect for the potential customer and sometimes there is no product at all yet!
Some product changes often have to be promised to close a big sale, and there is a strong demand to get those changes done quickly so as to give the new customer a great impression.
Because of this I understand that when contracts arrive back at a company they tend to be a little bit optimistic, I really do. Besides it gives us engineers a nice challenge that we enjoy as long as the changes demanded are interesting.
However sometimes this can go horribly wrong. The organisation ends up promising things that it can't possibly deliver, for a price that it can't possibly make a profit on.
One example was a sales team that promised complete localisation to a customer's language without realising that the speech recognition in the product had been custom engineered over sixteen years to make it perfect for one, English speaking, user group.
Sales people didn't feel obligated about delivery of the contract, that's what engineering is for! Engineers didn't feel obligated to deliver the contract either as if it's already impossible why bother trying.
The best outcome you can really hope for from this is that a bunch of engineers and sales people end up hating each other while failing to deliver a thing - with the new customer watching.
This is where contract and project managers come in.
It doesn't really matter what the role is called, the idea is that one person sticks with the project from start to finish. They pick it up directly from the sales leads and keep ownership until the final promise is delivered and the cheque has arrived.
These individuals don't have to be technical, as they can engage with engineering for answers, but they do have to know they are fully responsible for the eventual results to ensure that they are motivated to really understand what they are being committed to.
Because they do this early they can usually brush off the optimism of the sales guys before expectations are too firmly set, or at least before deliverables are signed into the contract! Engineers will also make promises to them personally and feel committed not to let them down through delivery.
There are other reasons why your organisation needs project managers, but as in this example it frequently comes down to making sure that one person feels responsible for success and will ensure that the necessary conditions occur to allow work to get done.