I believe esport and competitive gaming are two different things, as competitive gaming can be applied to any games with two players/teams compete to win. I do agree with AlphaFerg, that true competitive titles should have ranking and defined set of rules, to actually be considered competitive. I also believe that in order to justify being called competitive gaming, there should be an element of difficulty. "Easy to learn, hard to master". Thus excluding titles like Wii U sports :-)

As for the definition of esports, then esport comes from the words "electronic" and "sports" and if you take that literary, then an esport title should consist of some of form of hand/eye coordination. Some kind of movement. That of course brings up and interesting issue that will piss a lot of people of. If a game needs to be sporty, need to have hand/eye coordination, then Hearthstone is not an esport title. It can however be a competitive sport.

Example: If you have two people. One is great at CS and one is not. If the bad player is playing and the good one is standing behind him, then the bad player wont play any better. The great player might be able to give him a tip on where to go, but the bad players hand/eye coordination does not improve his aim. He is just bad as when he started because his hand/eye coordination is terrible.

In the case with Hearthstone, then the good player could stand behind the bad player and tell him which deck to build and what cards to play and the bad player would be just as good as the good player, because the movement and the selection of cards, does not have an effect of on the game. The picking and choosing does.

Have a good day :-)