Ericsson's contract isn't bad. He's a modern day Brad Stuart. A top four, stay at home defenseman is going to cost you 4.2 million these days.
I agree that he's in a little over his head as a top pair defenseman, but that doesn't make his contract bad. It just means we don't have other options, he's been forced into a role he isn't suited for, and has been exposed a little as a result.
Edit: For comparison's sake, Ericsson plays nearly the exact same role, with mostly the same results, for mostly the same money, as guys like Dennis Seidenberg and Willie Mitchell. Each suffer from many of the same pitfalls and shortcomings as Ericsson does. None of the three, by the way, should be top pair defensemen.
I think of him more as a modern day Lashoff but I only go off his play the past few years.