Replacing failure - no matter the talent potential being removed - has a way of getting the message across to change or lose your job. I know what it's like in high school being shoved into a varsity game because we needed to churn time and the guy in front of me was too soft on running downs. So, yeah, coach put my 180 pound sophomore ass out there to replace a 230 pound guy. But when it came to brute drive blocking, that was sort of my cup of tea. Both of us beat out the senior that wasn't using technique. On the next drive he was back in because he knew the plays and I really didn't. My sophomore year was pretty much my first real year of learning football. It made sense to have the big junior that knew the playbook in for most of the plays. But in specific circumstances, put the inexperienced guy in. And in every instance that mattered, sit the guy not doing his job.