Davis never played anywhere else.
Gary tore his ACL and was a FA signing @ Buffalo who was traded to Detroit for nothing.
Anderson signed with the Ravens @ 33 years old because they had just lost Chester Taylor to the Vikings and thought they were losing Jamal Lewis as well. He got a decent contract for his age, but it was an emergency signing since they had no proven RBs on their roster at the time.
Travis Henry was a stud RB with the Bills and had a good season with the Titans before going to Denver.
This notion that the Broncos churned out a bunch of RBs who left and were busts elsewhere has no basis in reality.
Henry as a starter in Buffalo - 4.5 and 4.1 YPC.
Henry as a starter in Tennessee - 4.5
Henry in Denver (one year) - 4.1
Anything else you'd like me to check?
I don't want to get into a pissing contest over what the numbers say when anyone can read them for themselves, but I disagree with your use of them and conclusions, and think you ignore some that are important. As a Bronco, Gary ran for 1,159 yards and 4.2 ypc as a rookie in 1999, Then he was running for 6.2 ypc when he tore his ACL in 2000, played two more years rushing in Denver for 4.0 ypc and at age 28 was traded to DET where he failed miserably despite high Lion hopes and had less than 400 yards and a 3.4 ypc. Anderson didn't play in the NFL until he was 27, but as a Shanny Bronco at age 32 he had over 1,000 yards at a 4.2 clip. The next year he was traded to BAL who hoped he could be a starter, but he couldn't beat out Lewis at the low ebb of his career when he was coming off a 3.4 ypc season and having a 3.6 season, and Andersonmanaged 183 yards. You choose not to mention Tatum Bell, who was a head case, but had 2 years or 900+ and 1,000+ yards and a ypc of 4.9 under Shanny. Then, he got traded to the Lions at age 26, couldn't win the starting job and kind of lost it - not that he probably ever had a great grip on life. I'm glad we now agree Travis Henry was a Shanny Bronco, and I can see why you chose to only take his numbers from the 3 good years in BUF and TEN when he had a ypc well over 4 and say he was as good or better there as in Denver. I add in the 3 bad years in BUF and TEN when he had a ypc at 3.5 and couldn't even take over the starting role and see Denver as a place he did better - but that situation was playing for Shanny after playing for someone else, and so probably isn't a great parallel for the Morris situation anyway. Droughns had his best year as a Bronco with 1,240 yards and a 4.5 ypc average at age 26. He was then traded at 27 to CLE where he had one good year with almost as many yards but a far worse 4.0 ypc than in Denver, and then 2 years below 3.4 ypc before disappearing. With Portis, Gary, Anderson, Bell and Droughns, the five Shanahan backs who went from his offense to another (all but Anderson at ages 25-28), each one other than Portis did far worse in the new system.
It doesn't mean Morris won't do better in his new offense, but I think its a solid trend and something well worth taking into consideration.