I was bumped off a LAX to ATL flight about a year ago. Every Delta flight going east was also oversold that same evening. The gave me the $400 voucher and put me up in a hotel. I returned the next morning and made my very early flight. Two other DL flights were oversold that morning.
A fellow bumpee told me that for DL, LAX is both high yield and unpredictable about the show/no show rates.
I have been bumped by DL out of LAX several times in the last two years.