I am a big fan of Mason! The element here that figured into the Todd Gurley pick might be more involved as rest of the Ram RB'ers, not in any part of Mason' abilities.
Last seasons starting RB Benny Cunningham just did not perform the same as he did in the relief role in his rookie season. In 2013 he averaged 5.6 yards a carry in 2014 he averaged 3.7 a carry. Benny also lost two fumbles in critical times. Benny did show he was a good 3rd down back & can catch the ball well.
It was apparent that Zac Stacy was on his way out & it came real fast. Isaiah Pead blew out his knee & is still involved in rehabbing & not ready. I would think that the Ram Org. had inside information on the Tre Watts suspension. As far as Chase Reynolds even figuring in as a regular RB in the rotation doubtful.
So in conclusion our overall RB cadre may have had way too many questions that Snead & Fisher could live with. Mason's play & or abilities may have not entered the picture much.
P.S. it would not surprise me if the Rams end up with 3 new rookie RB's on this team.