With the San Francisco 49ers unable to receive any production out of a No. 2 receiver, their offense has shifted to rely heavily on two backs and two tight ends.

The 49ers are using that formation with more frequency and less success.

The 49ers had a 60.3 percent success rate in 2012 compared to 44.7 percent this season.

Michael Crabtree is expected to return in the near future, which the 49ers expect to open up the offense.