Two observations:
Cali QBs leaving the state reflects the modern reality that USC, UCLA, Stanford and Cal are not now competitive on the national playoff scheme. Ever since Pete Carroll left USC, the Cali schools have lost their national stature.
In addition, the cultural trends in Cali (not an SEC atmosphere) and change in ethnic mix towards growing Asian and Hispanic populations has reduced the supply of top high school football talent. Ex. Long Beach Poly was famous for many years as the top producer of NFL talent among all US high schools. No more. Poly is now 50% Hispanic, 20% Asian and just 15% Black. This mix seriously reduces the pool for football talent.
Impact. There is enough football talent in Cali to supply a bunch of colleges. But, you gotta find it and recruit it aggressively. TheCanes have landed J Phillips, K Smith and J Garcia in the last 3 cycles. Great job. hope we can continue to mine this state for top talent!