His development was pretty much a done deal before he arrived at BYU. He also played much of the season hurt, which affected his performance and numbers. He did develop pretty well for a 2* guy over his career, though.

As to the others...

Unga was a 2* recruit who became a star for BYU and had a shot at the NFL. Hard to say he didn't develop well as a player.

Hoffman was a 2* as well and hardly recruited out of HS, ended up a great college WR who also got a look at least by the NFL. That's also development.

Mahina was a 3* TE who really fell victim to a change in offensive system that featured less TE.

Stout was a 4* who struggled with the BYU environment. These struggles cost him a lot of PT and hence, a lot of development. I'm not sure how much you can lay honor code stuff at the feet of the coaches.

Sampson and Daniel were JC guys. They're always a crap shoot as to how they'll progress in a shorter time window.

Bottom line is that most of the guys you mention, outside of Stout and Mahina, weren't highly regarded recruits. Stout was his own worst enemy and Mahina suffered from an offensive scheme change and was fairly old for a potential draftee.

I think BYU's coaches do a dang good job developing players. As the church grows and BYU's great TV exposure continues, recruiting should improve. Up until the past couple of classes, most of BYU's recruits grew up during the MWC/the Mtn. years where BYU was essentially invisible on national TV. We now are a weekly staple on TV and that should enhance recruiting significantly over time. That said, we'll still have the same limitations and cultural restrictions and there may well be a glass ceiling on how high BYU can go in recruiting new talent.