McCluster, who likely will not be too expensive, can help as a returner as well as a receiver. The Chiefs had high hopes for McCluster, who they took in the second round in 2010, but he never made a huge impact for them on offense. He is, however, versatile and can play running back as well.
The 49ers already have their own second-round player who has yet to make an impact. Oregon running back LaMichael James, who was taken in 2012, is a similar player who hasn't been able to make his mark. If would be interesting to see what the team would do with James, who finished the season as the return man, if the team does pursue McCluster.
There certainly could be a scenario where both were kept. I don't think McCluster would be a priority, but I do think he could be somewhere on the team's wish list.