The crew has done a lot of things. A heist isn't one of them. It's like asking the fire department to steal a bunch of jewels. Which would be a great movie by the way, but not something these guys are used to. 

To be fair, lots of heists are attempted by first timers. Otherwise you wouldn't have heists by old pros. So there's a chance the crew could pull this off. After all they have many of the skills necessary to pull a heist. They've just never put them all together and applied them to this particular context. But there could be a lot of success in these guys' future.