Hmm... it seems like that "ton" here is used as a verb.
None of my dictionaries mention the use of "ton" as a verb.
The meaning here seems to be that the 19 one-day really demonstrates, proves without a doubt how easy it was for her to play the game.
Extremely easy. If you do something with effortless ease it's so easy for you that you don't even have to make an effort.
Student or Learner