In defense of Allen (gulp)

I want to know why he gets blamed for the bad tackling. These are grown men, professionals, that have been playing this game for a while. Does he really need to sit them down in a meeting room, tell them not to eat the crayons, and then go over tackling 101 again with them?
He's a coach right and coaches do things like practice drills and party attention to details. This team is composed of 90% of the players from last year and only one major thing changed- a new HC.