Cost of delay nearly three times the cost of the switch?

The Centers for Medicare and Medicaid Services estimates (warning: PDF) that delaying the switch to ICD-10 will cost as much $6.85 billion.  However, its original maximum estimate (see page 3361, warning: PDF) for the entire switch itself was $2.3 billion.

So we're supposed to believe that a one-year delay will quadruple the cost of the switch?  When CMS wants to switch to ICD-10, it's a mere $2.3 billion, but when CMS gets mad about a Congressionally mandated delay, suddenly the delay all by itself costs $6.85 billion?

CMS estimates low when it wants to do something, and high when it does not want to do something. How petty.