^^^^
Just my 2 cents on the "speed" argument. "Speed" between the ears is more important then any physical speed.
The best defenders are the ones who are not blessed with athleticism (though that does help) but the ones who read the game really well and are one step ahead of their attackers. For example Boogs' bad discipline record is not because he is an overly aggressive player, it's mainly because he gets himself in positions where he has to make a rash split-second decision such as a miss-timed tackle or having to commit a professional foul by shirt-tugging/holding etc.
He can look back on his discretions from last year and hopefully learn from them and be a bit smarter this season but the truth is most defenders (and players in general) either have or don't have this uncanny ability to read the game.