After reading recent interviews with LMJ and Jenkins and reading about them not getting playing time right away in college makes me think that Baalke and Harbaugh knew it would be hard for them to see the field their first year and they got guys who have been through it before
LMJ interview http://49ers.pressdemocrat.com/2012/10/inside-the-49ers/lamichael-james-i-dont-know-the-game-fully/
Q: You haven't played yet this season. You didn't play much your first year at the University of Oregon, either. Have the two experiences felt similar?
JAMES: It's the exact same thing. I went to Oregon and I had to work my way up – from the scout team, running plays each and every day and really not expecting to play (in the games). And then you get your opportunity and you have to go out and prove that you can help the team win. Right now I'm just learning. I have great players in front of me. Frank Gore – that's one of the best running backs out there – and we have Brandon, and we have Kendall. They're all really good. I learn a lot from those guys, just like I learned a lot from LeGarrette (Blount) at Oregon.
Jenkins interview http://blog.sfgate.com/49ers/2012/10/23/a-j-jenkins-its-a-humbling-experience/
It's humbling," Jenkins said. "It's a humbling experience. You're drafted in the first round and people tell you how great you are and all the other stuff. But when reality hits you, hey, right now it's not my time to play, you kind of put things in perspective. I'm humble right now." Jenkins was active for the season opener at Green Bay, but didn't step on the field. He's since been inactive for six straight games while two rookie receivers selected more than 10 spots after him – Chicago's Alshon Jeffrey and the Jets' Stephen Hill – have combined for five touchdown receptions. Last week, Mario Manningham was sidelined by a shoulder injury, but Jenkins remained on the sideline and 49ers dressed four wide receivers. Fortunately for Jenkins, he's been here before: After his first two seasons at Illinois, he was a backup wide receiver who had 26 career receptions and a burning desire to transfer to another school. In retrospect, Jenkins said he learned as he waited for his turn. He believes he's doing much the same thing this season as he picks the brains of the veterans and picks up tips by studying film snippets of wideouts such as Johnson and Fitzgerald.
I know it doesnt make it easier for you guys who are dying to see them pla but these are a couple of guys who never had anything handed to them, they have had to work hard to get where they are at. Im sure they will be ready when called upon whether thats this year(unlikely) or next year