According to the Frisco Bowl web site, the LA Tech vs SMU game in 2017 drew 14,419 fans, which was more than the FB games in 2018 and 2019.
December 20, 2017 Louisiana Tech 51 SMU 10 14,419 notes December 19, 2018 Ohio 27 San Diego State 0 11,029 notes December 20, 2019 Kent State 51 Utah State 41 12,120 notes
I think it's also important to remember that Toyota Stadium --the Frisco Bowl game site-- was under construction in 2017, and therefore seating was more limited than usual. Below is an actual photo of the 2017 game crowd: