Not entirely sure. But google tells me Jabotinsky Day, a national holiday in Israel, falls on July 28th this year. It woudl start at sundown on July 28th and end on the 29th at sundown. So by pushing the flight back to an 11pm departure from SFO it causes a 11pm arrival on 7/29 in Israel and avoids any issues with the holiday? Just my uneducated guess. But also looking at the schedule for 7/27, the 8pm departure would arrive in Israel at 8pm on 7/28, along with the ORD and EWR flights arriving in TLV in the afternoon of 7/28 & 7/29, which would seem to go against that idea (depending when sundown is on 7/28 in Israel?). So maybe someone with more familiarity with TLV operations/Israel culture could weigh in if this has anything to do with it, or just a happy coincidence.