Jobs left Apple in 1985, and there hadn't been anything but one model of Mac by then, and he wouldn't return until 1997. The PC-like explosion of Mac models and various peripheral projects like printers, cameras, and PDAs happened without him.
Of the time they did have Jobs at the helm, he had a remarkable track record with new products outside of their "core competencies" as you put it. This includes the Mac itself, which abandoned wholesale their existing lineage of computers and software for a pretty different paradigm tuned for the non-technical customer.
He had some failures. The Apple III, arguably the first Mac (it really didn't gain traction until Apple loosened on things like expandability and fans that Jobs didn't want), G4 Cube, iPod Hifi, Ping, 3rd gen iPod Shuffle, Apple TV.
Of the time they did have Jobs at the helm, he had a remarkable track record with new products outside of their "core competencies" as you put it. This includes the Mac itself, which abandoned wholesale their existing lineage of computers and software for a pretty different paradigm tuned for the non-technical customer.