Nelson is getting over a shoulder surgery and should be soon cleared to play. Maybe even this week?
Burkhart was a fantastic WR but injuries (concussions?) cut his playing days short.
The WR Knight you mention above is Boogie Knight, who is still on the team but lined up at running back now. He also returns punts & kicks.
I don't know about Sands. Didn't he graduate? I thought he was a senior last year, but I definitely could be wrong.
Edit: ^^I see Captain beat me to the punch! Lol