Injuries will happen during football. Proper weight training and conditioning can reduce that number but never completely eliminate them. I can see frustration surrounding a coach if he hasn't implemented a proper training routine. With that said, the kids have to buy-in and participate. Weight training and conditioning isn't something you can fake and make in relation to football.
I know a few programs where a proper training program was in place but only a handful of kids participated on a regular basis, which ultimately hurt the team. A couple of those instances, coaches were blamed by the community but the coaching staff can't force kids to participate. It almost always comes back to "want to" on the part of the kids in the school system. Reading between the lines, it sounds like maybe there is some of that going on here.