I'm not the most familiar with the programs, but Mike O’Neill has been with Rutgers for fifteen years, which means that he arrived at the same time as coach Crooks (give or take a year). He spent ten of those years as associate head coach during which he led the local club team to multiple nation championships, so he wasn't an unknown. The way coach Crooks put it, coach O'Neill could have left to become head coach somewhere else a long time ago, but wanted to stay with Rutgers, so I would assume that he is pretty solid.
As far as Donigan, he is a native of New Jersey (as is O'Neill), and he left a team that he coached to seven NCAAs in nine years, so there is certainly something that brought him here. Of course, money is money.