Last year Kelly played 8 guys at WR. All years he's played 6-8 guys.
Right now ND has 6 guys that have played WR:
ESB
Boykin
Claypool
Sanders
Finke
Stepherson
They also have McKinley (who is coming back from a bad injury) and 2 true freshmen, neither of which will be here in the spring.
The depth chart definitely needed 1 more guy, especially that could play the X position (which lost Hunter and Holmes).
Conversely ND has Watkins, Crawford, Love, Vaughn, and Pride at CB, not to mention White and Coleman (who are rumored to be moving to safety).
CB will be a major need in the 2018 recruiting class, but is not a need for the 2017 season.