He was out of fuel sooner. The last ping really doesn't define when exactly flight ended, we don't have this data, not yet.
I know we don't have anything concrete yet but I thought there was a relative, rough consensus that the partial ping occurred at the time of fuel exhaustion as what else but an engine shutting down could have triggered it?
The only thing that sort of explains the "flew faster in the same amount of time, ergo, flew a shorter distance," that I can think of at least, is that the westbound leg was flown faster than previously believed, leaving less fuel for the southbound leg, which meant the southbound leg would have had to have been flown at a lower thrust setting for the a/c to stay aloft until the partial ping.
???