The linchpin of the Streamlined Process is the willful / non-willful determination.

1. Preponderance of the evidence
2. Clear and convincing evidence
3. Beyond a reasonable doubt

now which one will it be outside of McBride,Williams or Zwerner ?

Another practitioner discussion of the willful / non-willful continuum and uncertainty in the New New Streamlined:

What happens if IRS says my conduct was willful?
Bad things can happen and apparently there is no appeal from the IRS determination about one’s eligibility for the Streamlined Process.  What happens then if you are kicked out of Streamlined?  Some consequences:

• Your returns for all open years under the statute of limitations may be audited, not just the three-years filed.  If fraud found, all years are fair game for audit. Thus, you may be assessed substantial additional income tax.
• You have no criminal protection for FBAR and income tax violations.  Thus, you can go to jail and expect IRS to make some examples out of some filing frivolous non-willful certifications.
• You may be assessed the maximum income tax penalties including late payment, late filing, accuracy related and/ or civil fraud penalty..
• You will have appeal rights with regard to the income tax penalties proposed or assessed upon examination.
• IRS may assess the FBAR penalty but will have to sue you within two years of assessment to collect as the income tax levy procedures do not apply.
• You may be charged with perjury for your false certification of non-willfulness. 
• http://the-tax-wars.net/2014/09/01/will-o-he-wisp-non-willfulness-in-the-streamlined-filing-compliance-procedure/