Usually there is some sort of RFI process, where they ask a few companies 'hey can you build this for us? What are the types of services you would propose'. The list of companies here is already more or less pre-existing partnerships, or ex colleagues or...
(it mostly always contains Microsoft, and your boss is ex Accenture, so it involves Accenture, and for good measure to seem like they are open to other options they invite Deloitte and some other players as well, sometimes even IBM has joined the club again)
Then they decide who they deem thrustworthy, and you end up with Microsoft and (insert boss previous employer). So not only do you not get the lowest bidder, you can some veeerrryyy generic company that doesn't care and just sends juniors to solve it. This process is called the RFP. And it typically is far from neutral