I'm not sure there is any kind of agenda. I think MOS believes he is putting the best football team on the field, he just has a different way of going about it, where he values experience, character, and attitude more than a typical coach might. And this makes him loyal to players... to a fault.
But I'd also point out that rookies DO make their way onto the Bombers eventually. It's just usually not on day one, and at the expense of an established veteran. This management/coaching team seems to like bringing guys along on the practice roster for some time before giving them spots over veterans. If you look at guys like Devin Adams, Jamal Woods, Bridges, Randolph, Vanterpool, Wheatfall, Ayers..... they all came in last year and may not have been on the team day one or roster regulars but now they are. There's a good chance guys like Cam Allen, Woodbey and Cooley play big roles this year or into the future.
But Evans should have made it over Sheahan, sick of Sheahan.