Look at it this way: Your job is filming practice, so you see basically every instance where Kelly loses his shit because a player didn't do his job. You have a pretty plum job. Probably pays OK and you can brag to everyone you've got the kind of insider access to the program rarely found even in the media. Kelly probably goes apeshit a lot, and you know that, unlike the guys in pads he's going apeshit on, you're perfectly replaceable and those guys down there are at least trying to do their jobs. Whereas if you call it quits in the middle of practice, somebody else will be getting your paycheck posthaste.
Point is - it's a lot more than "some external pressure." And probably a lot of internal pressure too.
I sort of have my doubts those guys report directly to Kelly, though. Whoever that person is should be the first under the microscope and then go from there. I've never cared for the "fire the head guy for everything that could go wrong" attitude.