Can my bosses pay me my average pay legally simply because they feel like I made too much money on our production system?

Generally, no.  Your employer must pay you according to the pay practice for your position.  If there is a production pay system, then they must pay you according to that system.  Two things to keep in mind though. First, they can pay you in a different way than the production system and in a different way than your co-workers, as long as you are notified in writing that your pay is different.  Second, firing you for complaining about an unlawful pay practice would itself be unlawful.  However, that will not necessarily stop your employer from firing you.