Replacing Miller will not be a one man job. Let's take a look at how the 49ers coaching staff probably will and won't fill the role left open by Miller's injury.
1) Anthony Dixon - While Dixon has primarily been a halfback, the 49ers have worked to transition him into the role of backup fullback since 2012. During the 2013 preseason over 40% of his snaps came from the fullback spot. While Miller finished the preseason with a PFF run blocking grade of -1.5, Dixon wasn't off by much while finishing with a -2.5.
I went back and watched the snaps at the end of the Tampa Bay game after Miller went out and the block by Dixon on his first snap jumped off the screen. The 49ers ran their bread and butter Power O to the left side and Dixon not only made his block on the outside linebacker he absolutely blew him up, getting leverage and finishing his block with his man on his back.
Miller has proven to be a viable threat in the passing game this season in addition to his blocking. This is something that I believe we will see Dixon excel at as well. Dixon is a bit faster than Miller and should be able to turn those short flat routes that the 49ers like to run into bigger gains.
Another thing that jumped out at me as I looked at the film of their last 3 games recently was that they have utilized both Derek Carrier and Vance McDonald from the backfield a few times. Look for this to increase moving forward.
3) Will Tukuafu - On Wednesday the 49ers brought back the former defensive lineman turned fullback. Tukuafu, who will fill the backup fullback role, played 92 snaps in that role for the 49ers in 2012 and was given a run block grade of +5.5 by PFF. The one limitation with Tukuafu is in the passing game, as he was not targeted at all on those 92 snaps. The 49ers need to be careful not to telegraph the play should he be utilized.
4) Anquan Boldin - This one might seem a bit strange but let me explain. When Boldin was at Florida State he played a bit of everything and we have seen the 49ers do a bit of that with him this season. One example came last week against Tampa Bay. On the first play after Miller went out, they put Boldin in the backfield with LaMichael James, and gave him the ball on a play that could have been a touchdown had Adam Snyder been able to make his block.
Don't expect,
While the loss of Miller is big the 49ers coaching staff should be able to manage the team through it. Remember, this is a team that went through the first 10 weeks of the season with basically only 1 wide receiver.