[quote=@Assallya]
Ozzle came out of Hyperspace too early, putting them across the solar system.  Vader had assumed Ozzle would have emerged in high orbit to take the rebels by surprise.  In response Vader executed Ozzle and promotes Piett.
[/quote]

I always enjoyed that theory that Ozzle did it on purpose because he was actually a Rebel sympathizer. Probably wrong, but it's still amusing :V