I have no worries about Keenan Davis. Maurice Brown jumped onto the scene as a JR too ... and that was after being caught behind Kahlil Hill and CJ Jones when he was a SO.
Keenan was caught behind a very solid trio in McNutt, DJK, and Sandeman. With DJK and Sandeman now gone, a lot of reps will open up and Davis will likely be ready to take advantage.
Also, in many respects, Vandenberg is even more of a "passing QB" than Stanzi was. Thus, I anticipate that that could end up translating to more grabs for our WRs too.