Trask is a strong 3rd in that chart. That chart is anchored on passing yards but Trask is light several games since Franks started the season. Had Trask played all the games, he might be pushing Tua for 2nd.
Statistically, it should be Trask. Mond is only better in total yards (barely) and played a lot more snaps the first couple of weeks. It would not surprise me in the least if it ends up being Fromm.
If it is Trask, would he be the preseason #1 next season? He would be the highest rated returning QB.