Found this in the Big Shots thread:
All of the 10 p.m. dramas declined as well, although "Without a Trace" (14.5 million, 3.8/11) came in a nose ahead of ABC's "Big Shots" (8.7 million, 3.7/10) and NBC's "ER" (9 million, 3.7/10). Last week, "Big Shots" premiered with 11.1 million viewers and a 4.5/12 in adults 18-49.
And from pifeedback for October 25 which is episode 5:
Grey’s Anatomy (Viewers: #1, 17.95 million; A18-49: #1, 7.3/15) and Big Shots (Viewers: #4, 8.08 million; A18-49: #3t, 3.3/ 7). Retention for failing Big Shots out of Grey’s Anatomy was just 45 percent in both total viewers and adults 18-49. And the loss of audience for Big Shots at 10:30 p.m. was a hefty 2.10 million viewers (9.13 to 7.03 million) and 26 percent among adults 18-49 (3.8/ 7 to 2.8/ 7). Tick, tock…the cancellation clock is ticking.
It looks like the fact that Big Shots wasn't holding on to Grey's audience is what killed it, only keeping 45%.