I'm just a layman, most of my practical, visual understanding of Caesar's campaigns comes from Historia Civilis, so I'm pretty basic here. But it seems I'm not the first person to get the idea that Caesar's men weren't the most competent - Frequently allowing the enemy to take the upper hand (say, to build a stone wall or occupy the hills) the moment Caesar has his back turned.
Is this true, or a misconception?
It's true that Caesar, to various degrees throughout his career in Gaul and the Civil War, was in want of men whom he could really trust to be competent in their roles. It should also be considered, however, that Caesar was really demanding competence from his staff in a variety of fields. Antony is a great example of this; he was a very good military leader (e.g., his role at the Battle of Alesia) but when Caesar left Antony in charge of Rome while he chased Pompey to Greece, Antony left much to be desired.
Even if you confine the question to only military matters, remember that Caesar himself is the author of our best sources about much of his career, and it's in his interest to take credit for all his army's victories and blame others for its defeats. This may result in his commanders looking worse than they really were.