This is a courageous and smart move to put your question forward.
If you want to get a success out of this team, make sure that you agree with them on company core values, core objective, and derived team core values and team core objective. Further agree with them on what your team’s added value would be for the company. Then discuss with them who will be doing what in creating that added value, and agree with them (the group) on how to reach your goals or objectives. This way, it will be a shared responsibility, where they will support each other to reach best results.
Use the “Now, discover your strengths!” test from the Gallup Organization to find out what each individuals’ talents are, and decide with them on who will be doing what, based on their talents (or themes as Gallup calls them). This will allow them to see that you are genuinely trying to make the best of the situation, and have their well being and successfulness as a prerogative for the teams’ success. Look at them and coach them to perform as well as they can in their individual roles. Leave ample room for personal creativeness, but watch out for them “not breaking the bank."
Use the leverage you will “demand” from your superior to build this team (based on his assumption that this is a weak team) to create a period of build up to enhance the quality of this team. Demand a period for a year to build this up. After all, he is putting the problem in your lap! (Why didn’t he solve it himself?) Measure consistently on performance improvement, and use that to sustain leverage.
You might be astonished as to what the team might come up with!