Two things: they were smart to do this before Joe Burrow got done.
And…
Khalil Mack will be gone after this year. Keenan Allen will be gone after this year. Austin Ekeler will be gone after this year. Joey Bosa might be gone after this year.
The Chargers are going to have plenty of money to throw around and in 3 years Herbert’s deal will be like 7th in AAV while the salary cap continues to rise.
The question for the Chargers should be “how do they build a team without Justin Herbert?” They can’t and they smarty locked him up.