Because that's the program's history. The previous head coach wasn't the biggest disciplinarian, he was laissez faire relative to many other coaches with respect to keeping his players in line, and he put up with more than many other coaches might be willing to.
Not criticizing him, just describing.
The vast majority of kids in the rotation were recruited by the former HC, and played under him for at least a year. Red made some changes to the culture, which came with some new expectations -- and those new, more stringent requirements didn't sit well with a few of the players, who were accustomed to something else.
For the record, doesn't make them bad kids. But it wasn't what they signed up for, and wasn't what they were used to. So they chomped at the bit. And those three are pretty tight, so they became somewhat of a passive aggressive disruptive element, even though they weren't overtly "bad."
Red clamped down on some of it, so there WERE some consequences, and there was "control." He even booted a player [not one of the three described above] for repeated squireli-ness. And for a time, that got the attention of the others, and induced them to fall in line -- but it was temporary / short lived.
And now that we're at the end of the season, Red can be frank with them. Get with the program, or find a new place to play. Rest is up to them.