Couldn't agree more with this. I remember seeing him up close against BC and I couldn't believe how sluggish he looked when changing direction. You could tell he didn't have very good core strength at all and was carrying some bad weight. Once that improves he'll make much sharper movements and see his defense and rebounding improve quite a bit.
Probably going to lose quite a few people here and sound like a fitness nerd but core strength is a huge, huge piece of emphasis for high level athletes and it was evident he had a lot of work to do there. I know all the way from Duke basketball to Alabama football they preach that probably 75-80% of performing at a high level and having functional strength is done in the area between right above the knee to right below the rib cage. That's the foundation for basically all athletic and explosive movements. I mean just look at how the HEAT carved up Dion's mid-section and how he improved.
For example, when you watch really good high level defensive backs/wide receivers or basketball athletes change direction they almost always break down knees bent in an athletic stance, have their chest up and "lead" the turn with their belly button so to speak. Lydon often times on closeouts would be standing upright, with his shoulders hunched over and his shoulders would be the first thing to turn. Basically a textbook sign of a really weak core so the fact he has 13% body fat after preparing for the combine shouldn't be a huge surprise. An NBA team will tighten and strengthen that up real quick and he'll get better.
