Analyze Competitors Site - Figure Out His Onpage SEO - Duplicate For Me - Then Crush Him!

I have one main competitor. He's sort of an evil genius with WP. Unfortunately, he is in the same industry as me NOW. He used to work for me. He's destroying me in the rankings and traffic but only ranks high for lots of low volume keywords. He's a cheap guy so I know he doesn't spend a lot of money on plugins, ads, or seo. I've figured out a few of his tricks but don't know what works and why. Anyway, mainly concerned with uncovering his onpage seo tricks and having someone guide me thru and help me duplicate them, one by one. I've uncovered a lot with seobility and sitebulb actually. Only expert SEO sleuths please. I've wasted too much time already and need to start catching this guy. Also, he DOES NOT have very many links so I think it's mostly onpage stuff that he's doing. I'm not posting my domain or his publicly. I don't want him to catch on. He's a sneaky bastard. I know he basically just copied all my old keywords and now is killing me for keywords that I used to dominate for. Just rebuilt my site and the rankings are down while google get's their shit together. Only experts please. Must be a good communicator in english. I'm sure my onpage linking structure sucks right now. Anyway, let's talk. Thanks