Gabe Encinas at SB Nation wrote a story on the group earlier this week focused entirely on the top 6 returning receivers.
I'd break down the receivers into different tiers. First, the guaranteed starters Cayleb Jones and Samajie Grant. Both will be looking to prove they are not just the best on the team, but 2 of the best in the conference.
The next group are those competing to start - David Richards, Trey Griffey, Nate Phillips and Tyrell Johnson. I could make a case why each player could end up in the starting 4 and the ones who start could change each week depending on match-ups. If I had to guess now, I suspect Griffey and Phillips will end up the starters, but Johnson's explosiveness and Richards' size and consistency will push to make them starters. In the end it doesn't matter who starts. All 4 of these guys will be essential parts of the wide receiver rotation and each one could lead the team in receptions in any given game.
To me the most interesting group is "who will fill out the rotation"? The only other returning receiver from last year is Jonathan Hayden (1 catch) and he may end up as a running back instead of a slot receiver. Competing to be part of the rotation this year will be one redshirt Freshman, Tony Ellison, one redshirt Sophomore, Abraham Mendivil, and one true Freshman who enrolled early, Jordan Morgan. Because of their time in the system these 3 receivers are the most likely to see playing time, but there is also the possibility that one of the true Freshman comes in and competes right away like Phillips did in 2013. The Freshman arriving this summer are Shun Brown, Darick Holmes, and Cedric Peterson. Someone in this group is going to fill out the receiver rotation and right now it is a wide open competition.
81 is also the distance of DaVonte' Neal's punt return for a TD against Wash St as well as Will Parks' total number of tackles in 2014.