Well they are certainly not weak. Blackbeard is being set up to become the "last boss" for Luffy to fight over One Piece. He is a D but not the right D, a false messiah if you will. His crew mates are starting to mimic Luffys team. Sniper/Usopp, Wrestler/Franky, Shiryuu/Zoro, Doc/Chopper. And i bet one of the new guys will use hand to hand combat for Sanji and they have a girl which will be perfect for either Nami or Robin. So these new crew members will rival that of Luffy's at the very end. And i don't think they will be weak at all. And Zoro is aiming to be become the greatest swordsman to ever live by beating Mihawk. And once Blackbeard and Luffy faces off Zoro will probably have done that. And once they face of Shiryuu will be on the same level as Zoro. Or else it would be kind of one sided. And just because they where in prison doesn't mean they are weak. Who's to say they didn't face of against an admiral to end up there. And right now very few seems to be able to stand up to an admiral. Among Whitebeard's crew only 2 seems to have had that power and that was Marco and Whitebeard himself. Ace and Jozu was both beaten. Marco only lost because he was distracted and they managed to get seastone-cuffs on him. Even though Jozu could have been distracted i feel he would have lost either way in the end.

And he didn't throw away anything. Like he said himself. Only reason he needed that title was so he could get his crew mates. Once he had them, he didn't need or want the title. If he never had wanted the prisoners he wouldn't even have tried to get the title in the first place. Every step Blackbeard has taken so far has been just as he planned. In fact having that title was probably a "burden" (can't seem to find the right word to describe it, too early i guess). Blackbeard plan to become the Pirate King. And what we have learned is that Shibukai's are considered traitors to other pirates since they have struck a deal with the WG. But in Blackbeards case that has been redeemed because it was even announced to the world (assuming the Den Den is still broadcasting) that he only used the title to deceive the WG.