This article was originally published on GameSpot's sister site onGamers.com, which was dedicated to esports coverage.
"Popularity" is determined by picks weighted bans. (Weighted bans meaning if a pick could be played in multiple roles, the ban was divided between roles based on the pick rate of the champion each role.)
To see this same graphic for last split check out this post: http://www.ongamers.com/articles/data-visualizations-for-na-lcs-spring-split/1100-1274/
Data collected with help by the onGamers Stats team: Derek 'Kathix' Adams, Jesse 'JALbert' Albert, Steven 'whedgehead' Falgout, Kent 'Traepoint' Frasure, Christoph "geilerHarry" Lansmann, Jake Morales,James 'PelkaSupaFresh' Pelkey, and José "Vodkita" Ribeiro. Design by Ben 'Sarcasmappreciated' Li.