Seattle Seafair TFR question

Just a curiosity, the Seafair TFR has two parts:

• 2 NM radius - SFC to 5000
• 5 NM radius - SFC to 16000

The larger TFR becomes active 2 hours before and ends 2 hours after the smaller one, and they both start at SFC, so why is the smaller TFR necessary?

Again, just asking out of curiosity.