https://www.pcgamer.com/rainbow-six-siege-game-director-talks-castle-and-thatcher-balance-reworks/

Morgan's tips for playing Rainbow Six Siege’s newest operators are a sure fire way to master the squad shooter's freshest faces. Designing new combatants seems like a daunting task—but game director Leroy Athabassoff explains reworking them post-launch is equally important and can be trickier still, particularly once players have settled into certain playstyles.  

To this end, Frost, Castle and Thatcher are in the process of being reworked.