trade Matthews and Harvin for Fitzgerald?

12 team standard league 2rbs and 3wrs.. My 2 RBs are Forte and Peterson and if i trade Matthews all i will have as backups will be Spillers and Ingram. Harvin is my #3 right now. I have St. Johnson and G. Jennings as my other 2 WRs. I also have Devery on my bench. Just curious if I should make my starters as good as possible and not worry about my bench or if I should worry about my lack of depth. TIA