J.I.S.M.

I have handicapping systems for everything of relevance, and Scrabble is no exception.

Using a grading scale where large mistakes count as 1.0, medium mistakes counts as 0.5, and small mistakes count as 0.2, we can reasonably assess how well a person is playing in very plain, relative terms. Using JISM, we can comfortably assess the odds someone will win a tournament. 

2350 - Perfect Player (does not exist)

2300 - BestBot (the best Scrabble computer engine, at woogles.io)

2250 - Nigel Richards (the greatest Scrabble human of all time)

Here are the mistakes/game estimates for each corresponding level of play.

2350 - 0.0

2300 - 0.2

2250 - 0.4

2200 - 0.7

2150 -  0.9

2100 - 1.1

2050 - 1.4

2000 - 1.6

1950 - 1.8

1900 - 2.1

1850 - 2.4

1800 - 2.7

1750 - 3.0

1700 - 3.2

1650 - 3.5