I’m not exactly sure where you got the stats to support that Fender didn’t sell many basses in the later 70’s, I sure didn’t see that many less.
If you talked with guys selling basses at guitar stores, they'd tell you that Fender was pretty much dead - they wren't selling. By the early to mid 80's it got bad enough that Fender itself would have agreed - they had shut down their American production in response to dismal sales; all they were selling was imported Fender Japan stuff.
