Analyzing 973 games played by the top 165 Garen players worldwide over the last 7 days. The average rank of the top Garen's was Diamond IV.
Taking into account win rate and summoner rank Garen is ranked 132 amongst all champions in the hands of an expert.
A minimum of 50 ranked games on Garen and Diamond Rank and above is what is required to be on the list. Rankings take in consideration win rate, current rank and number of games played on the champion.