Sometimes outsourcing lets "them" focus on efficiency and getting the details right and so you are better off. Sometimes out sourcing cuts quality to get better costs.

There are many accountants, it is relatively standard across industries, and so you can outsource it all easily - but most big companies have it in house anyway. (though they will hire out some of the grunt work) This is one area where messing up will kill your company so you better keep a close eye on it. (An accountant can easily steel enough money that you can't maintain cash flow - you might get the accountant in prison but your great company is bankrupt anyway). This is but one example of many cases where out sourcing is bad.

On the other side power utilities outsource most tree trimming around power lines. The companies that do this work give the utility a great deal because the contract that keeps their crews busy 3/4ths of the year which is important because most of this type of work is right after a storm and employees are easier to keep when they aren't laid off 3/4ths of the year waiting on the next job.

When an out sourcing is borderline not worth it because of risks above it, it may become worth it after this change.