When to bring IT in house?

My company currently outsources IT. We recently expanded and have more employees, more applications, more needs. I don’t think that we are getting the kind of tech support that we need as it is, forget about when we add more people and new applications. I would like to suggest to the management that we hire someone in house to manage our network, provide IT support, etc. First, is this the best idea and second, if so, what kind of info would I have to give to the decision makers in order to convince them?