Depth of Football Team

This year's Lamar football team is lacking in depth to the point where they are playing a bunch of guys who aren't ready. My concern is why so many players with remaining eligibility off last year's team are no longer on the team. I know guys leave for a lot of reasons but, by my count, there are 21 players gone who had eligibility remaining. Given the limited number of scholarships at the FCS level, that seems like a lot. Gone from last year's roster are:
TE DC Arceneaux
DB Jalen Barners
LB Jarett Carpenter
LB Mike Coats
OL John Craven
DB Kevin Davis
DB Blake George
OL Joseph Gonzales
LB Cameron Hampton (has played this year)
WR Shane Hudson
WR Jordan Jones
RB Austin Krautz
DB Cardell Lue
OL Kanon Mackey (transferred from place new coach left)
TE Sam McGee
TE Duncan McVey (gave up football due to injuries)
OL Barrett Myers
OL Blaine Myers
OL Joshua Persohn
OL Trevon Simpson
WR Clayton Turner

7 -- OL
4 -- DB
3 -- TE
3 -- LB
3 -- WR
1 -- RB

Another 19 players exhausted their eligibility last year.