If you don't care to know about the details of IT, I'm going to bet that your IT is not going to work reliably

In the last while, I've encountered a few large enterprises that had chosen to outsource pretty much all their IT capability.  That is, for the most part, all the actual activity related to IT delivery and IT support are done by third-party vendors.  Full-time staff, for the most part, only manage vendor activities but don't do any of the activities themselves.

From what I can gather, the nominal rationale for the outsourcing is primarily about two things:

1. Reducing cost: The third party vendor costs less than in-house staff
2. Delegating risk: The risk moves to the third party vendors

What I suspect is the actual rationale is something along the lines of... 

"We have not been good at IT, we don't know how to fix it BUT if we outsource it, we don't have to think about it."

The problem is the subsequent phenomenon that inevitably occurs.  Because, the full-time staff are only managing and not doing, they eventually (and by "eventually", I mean "very quickly") lose the ability to understand what is going on.  Once they lose the ability to understand what's going on, they lose the ability to effectively manage.

Is IT being delivered and supported efficiently?  Can't tell.

Is our IT risk being managed effectively? Can't tell.

No reduced (overall) cost.  No shared risk.  No ability to tell this has happened.

Martin alludes to this lesson in Utility vs Strategic Dichotomy.

If you don't care to know about the details of IT, I'm going to bet that your IT is not going to work reliably.