Free throws are a variable, you shoot them to start a practice, throw in a competitive session, shoot them again after a water break, and then shoot them under pressure to go home.

Then you get to game day and shoot poorly and the assumption is that you don't practice them. Obviously, some players shoot them better than others, but on a given night, the free-throw variable works in your favor, and some nights they work against you. In a close loss they become more pronounced.

1/11 is abysmal under any circumstances, but just as good free throw shooting begets good free-throw shooting, bad free-throw shooting often spawns more bad free-throw shooting. It's a really painful way to lose.

Any player that can't consistently make FTs (say 66.6% for shooters and 50.1% for big men) at every point (beginning of practice, middle of practice, end of practice, during games, in street clothes walking past the gym if a coach sees you, whatever) should be required to shoot them underhanded at all time (practices and games) until they can meet those benchmarks.

 

There was an interesting analysis (Ep. 590 of This American Life podcast) of the physics behind shooting FTs this way and why most that could demonstrably improve their performance by doing so (Shaq) refused to do so because "it wasn't cool." At the HS level, coaches should have enough control over their players to say "If you can't meet this RIDICULOUSLY LOW benchmark, you're gonna shoot 'em underhanded until you do." I suspect a bunch of kids would eventually get better at shooting FTs and a few would decide to keep shooting them underhanded.