On first glance, I figured he was jumping up to swat at the QB or something and got tossed, which often happens to defenders when they leave their feet, but that's not what happened here. It's really a poor pass rush by Sio, bad play on his part. It happens, got to correct it. He comes in gets engaged with the bigger LT, with very poor pad level, is totally extended out to his toes and the guard comes over is able to get his pads in under Sio's and simply stands up tall and creates a fulcrum that the LT is able to pick him up and toss him pretty effortlessly.
What happened to Sio is essentially what's called a Tsuri Komi Goshi throw in Judo, he got tossed by his collar. Had the tackle done it alone he would have had to get his hips rotated and in and under Sio's center of gravity. You can toss some very big people around easy if you know how to use leverage properly. Except the tackle didn't need to work to get sio off balance, or get his hips rotated and underneath sio to throw him, because Sio got himself off balance, and the guard came underneath to create the pivot point. the tackle just needed to use his own momentum to drive him into the ground, I bet it felt pretty effortless for Mr. Flukey.
Sio did nothing to break the force of the fall either, I bet he heard some cracking and popping in his ribcage and had a hard time breathing for a few seconds after that.
Live and learn - get your pad level, leverage and hand / body / foot positioning right, or get thrown around like a rag doll.
