There are many steps that managers can take to build trust, respect, and productivity, but making nasty comments and degrading comparisons is not one of them. The irony is that his ranting about your team and raving about his previous employees is likely to be reducing your team's productivity.
While you can approach senior management, that should not be your first stop. Rather, you and some of your associates should meet with your manager. Let him know that you have been working productively in the past and are highly motivated to continue to do so in the future, but you need his help. Tell him that some of his comments are interfering with the team's performance. Be prepared to provide some specifics.
Listen carefully to what he has to say. It will be particularly revealing to see whether his response is one of defensiveness or cooperation. If he continues on the negative path, that is the time for you and your associates to consider visiting his manager. After all, senior management often reacts negatively to department leaders who act negatively.
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