Which players should KKR retain for 2018?

Most players will go into the IPL auction next season, but teams may be allowed to retain a few key performers, like in 2011 and 2014. Kolkata Knight Riders retained just Gautam Gambhir and Sunil Narine in 2014. Whom should they keep from their current squad? Swipe right for the players you think they should retain and left for those you think should be released.