There are several parts to this puzzle.. One is that low level offenders get worse in prison, particularly when incarcerated with high level offenders. The second is that many convicts serving time for low level offenses are actually very high level offenders.

 In 1995 a guy in the Barrow region was charged with Sexual Assault of a Minor in the First Degree. He had been having sex with very young children (under the age of 3) for over a year. After concerns about witnesses and alcohol and mental illness and developmental disabilities surfaced along with issues in the DAs office, he was allowed to plead guilty to - get this - Theft 4th and served a year under the plea agreement. Yeah, he was a low level offender and yeah, he did go on to reoffend and several women and girls paid a heavy price for his plea agreement down the road. But I don't believe that it was incarceration that caused him to reoffend. 

This is NOT simple stuff. Simple solutions won't work.