They have 1 fourth year, 4 third years, and 4 second year vets.
Here are the years that they marched with BC and then an educated guess about how many seasons they have left after 2020 (From left to right) :
David Parker : 19, 20 ; 1
Sebastian Martinez : 19, 20 ; 3
David Ware : 18, 19, 20 ; 1
Zach Wilson : 18, 19, 20 ; 1
Jared Baltazar : 17, 18, 19, 20 ; 0
Taylor McBride : 18, 19, 20 ; 0
Dawson King : 17, 18, 20 ; 0
Zach Plahitko : 19, 20 ; 1
Chris Jackson : 19, 20 ; 1