Not entirely true. Ton of metrics for toughness (and I am not talking about just hits, but rather more useful toughness like ability to win board battles and net front contests). Leafs also added a crap ton of toughness, and it didn't exactly get them anywhere (if anything, they did worse).
Leadership and confidence are not as easily trackable (you can track certain qualities and tendencies however). You are also talking about something that is extremely volatile and can change from situation to situation. The Leafs have had former Cup winners, former and current NHL captains, people with thousands of games of experience, etc. Did that matter? What do you suggest, adding more leaders? More Cup Winners? More people who know what it takes to win? You mean Bogosian, Muzzin, Thornton, Spezza, Foligno, Simmonds, Tavares...
Track it all you want... Or don't. There is very little you can do about how people will respond or react to tough situations. What you can do is control whether a player is good at hockey, and analytics can track that extremely well.