"O'Malley employed those policies when he arrived as Mayor (999), but moved away from them for the reasons stated. The number of arrests dropped each year in Baltimore as did the crime rate."
Arrests peaked in Baltimore in 2005, which led to the lawsuit in 2006. It was only after O"Malley left office in January of 2007 that we got a mayor and a police commissioner that brought arrests way down. It's right in your own quote:
Arrests in the city have fallen by the tens of thousands since O'Malley became governor, and the ACLU and NAACP said in the statement that they recognize that the current city leadership has taken steps to address the issue and "applaud those efforts."
As governor O'Malley had no control over the Baltimore PD. He wasn't a part of the "current city leadership" whose efforts were being applauded by the NAACP and ACLU. So to credit him with the reduction in arrests is absurd.