It is my understanding that he returned to Merck to provide one more opportunity for his lapdog "Junkyard Joe" to come begging to the master for another job. It was excellent training for Junkyard Joe - Roger left him twisting in the California breeze trying to run Amgen R&D of the Future. Well, as we all know Junkyard Joe could not run Amgen R&D of the past and that is why Roger reassigned R to a distinguished leader during the Junkyard tenure at Amgen. It follows that he had no hope of running R&D of the future at Amgen, or anywhere else...well, except for Merck. So after a period in the Amgen dog house, Roger sent out the silent secret whistle to Junkyard Joe - up perks his tail at the sound of his old alpha dog from Wash U. - it is his time to prove himself after all of the Wash U years as the second string under appreciated puppy. Yippee, I am going back to my old master.....wag, wag, wag....
I wish Junkyard well. His new junkyard job sounds like his old job at Amgen, I hope that it goes better on the second attempt....