I liked the idea at first, not having to bother with efficiency of single games, not having to decide whether to ride out the streak or keep ECR up. Sounded great. Now I am thinking, paying for extra ranked games is fine, it is probably uneconomically and will probably mostly be used to edge out another reward chest for the average player.

But my big no-go is the limitation of not being able to play without energy. In the bot discussions the team always says "who can decide who can play and who can't". Well, now it is an energy bar. When I started out I unknowingly was completely draining my ECR because I didn't know it even existed, which is admittedly a problem. However, I liked the game and just wanted to play, always seeing new cards, immediately renting some to try them out. If I would have hit a "you can't play, come back in an hour", I would have likely quit right there.

In my opinion you can't introduce the "you can't play ranked anymore" without making sure there is a way to play without energy. I just assume that practice matches don't consume energy, but I really don't think this is enough. I would suggest introducing a mirror to ranked, lets call it nether or something lore acceptable, which would be basically the same as ranked, just no energy and no rewards. I can't imagine that this would be a tremendously huge effort since all the code and systems should be there and you just have to do all your calculations with ECR == 0% or whatever. Seems low-hanging fruit and I am afraid without that you will get a lot of angry people who were looking forward to a big evening of splinterlands. I mean lets be fair, 25 games can be binged in 1 hour, especially when you are in the zone.

Of course you could just make another account to keep playing, same solution like with ECR, but that is a hassle for players who just want to enjoy the gameplay.

Related suggestion:
Allow staking of (max level?) cards to improve energy regeneration. If I have enough cards to support 2 or 3 accounts I really shouldn't have to move those cards around to have more daily games.