3,200 inmates being released on average 55 days earlier with (what I found looking this up[1]) the daily cost to house inmates being $129, that would amount to about $22.7 million of savings.
On the other hand, that is 22.7 million dollars in lost revenue for the company/companies running Washington's prisons.
When viewed from that perspective, the move to recapture those released early makes a bit more sense intuitively.
[1] http://www.ehow.com/about_5409377_average-cost-house-inmates...