He only had one count of securities fraud
Pretty standard sentence. He most likely would have got probation if it was not for the losses: Any conviction for a federal securities fraud crime can result in a 5-year federal prison sentence per offense. Probation. Probation is also a possible penalty for securities fraud, especially when there is only a single instance of fraud or it involves offenses which didn't result in any financial loss.
Schena is in a whole other stratosphere. Conspiracy to Commit Health Care Fraud and Wire Fraud, Conspiracy to Pay Illegal Kickbacks, 2 Counts Payment of Illegal Kickbacks, 2 Counts Health Care Fraud, 3 Counts Securities Fraud.
The courts really don't like conspiracies, and people that don't take accountability. Using Holmes and Balwani as guidelines Davila gave them the low end of the suggested range. Given what Schena has in front of him I would guess the expected range would be around 18-24 years. So he should not be shocked to get anything over 17 years.