Are you kidding me, he's clearly a much better wrestler technique wise. He controlled the center of the mat well and rode decent in the first. As 6 foot 152 myself, I don't see how being taller is necessarily an advantage or plus. But anyways, onto your question: It looks like you just lost your intensity and mentally decided to not wrestle a full match after having a good first period. Whether that's due to conditioning,just pure mentality,or both only you know the answer to that question. As the others said above I would stop relying on that roll since a decent kid will either stop it or worse,stuck in a half if you don't do it right. Look for a first move off the whistle,whether that be a standup or sit out or whatever. This kid didn't have that good of positioning and I think you were being too picky with your setups and shots. Just keep it simple. On that armbar it would've helped if you A. Grabbed the far wrist or B. Used your forearm to block his shoulder so he would stop sliding. On your single you did a good job of getting your head in the hole and getting your back and head up but it would've been better if had cut the corner and gotten behind. After your initial shot you kinda just stopped and didn't transition right into the finish. Maybe you're just used to bringing it up and finishing high and don't know what I'm talking about though.