Former USAO appellate chief turned National Review analyst Andy McCarthy uses the curious Dennis Hastert case to pull back the curtain on what is really going on with "sentencing reform."  He notes:

Mandatory minimum sentences and strict sentencing guidelines for serious offenses were enacted precisely because judges, often in collusion with prosecutors [Ed. note: and virtually always at the urging of defense counsel], were systematically releasing serious offenders, allowing them to continue preying on society. While the "man-mins" and guidelines helped dramatically reduce crime, the left-leaning legal profession agitated against them. One result is "fact" pleading -- the sort of shenanigans that we see in the Hastert case: a willfully false rendition of the facts in order to sidestep sentencing enhancements required by law.

That is what sentencing "reform" has in store for us. The proposals may call for careful judicial fact finding before a felon is released. But the law already calls for careful judicial fact finding when the felon is sentenced. What we frequently get, instead, is careful judicial evasion -- often aided and abetted, it must be noted, by the Justice Department. It may be that careful fact finding would result in the release of some prisoners who should be released; but the breed of "fact" finding we are apt to get from sentencing "reform" will result in the mass release of incorrigible, violent criminals.

McCarthy's article is a goldmine about how the federal criminal justice system works on the inside, and well worth your read.  Sentencing reform is getting as far as it is only because the public has no idea about how many breaks for criminals are already built into the system, though hidden from view.