Yeah, I think that chests must be hard to get, and that you should require to have mastery 7, because lets be real, mastery 5 is too easy to get, even if you dont play good the champion, for example, a dude who plays hinx since she started playing, and just use her, at lvl 16~18 she will have the mastery even if he doesnt really know the mechanics of the champion, fail all the skillshots or simply doesnt have map awareness, because mastery also should be about knowledge of the game, if you land skillshots, know the stats of your champ and the perfect moment to make a fight with other champ, and i think mastery 5 is way too easy to get and you dont learn all you need to know about your champ, I have Irelia at mastery lvl 5 and even tho, i fail a lot of times in the damage exchange because I dont know all about the champ and i can learn a lot of it, same with more complex champions like Yasuo, which im bad with, but just because I played him like 20-30 times since mastery champions came out, i have lvl 4 mastery with him (almost 5) and Im trash with him xD