Liversidge, on 2016-June-13, 07:13, said:
Really helpful, everyone. I now have a very different mindset. Until now I have had to resist the impulse to open 2♣ with 9 playing tricks in a minor or 8 PTs in a major holding AKQxxxx, but now have a better understanding about why, and can discuss it with partner. We need to spend more time studying modern Acol rebids - for example, the meaning (length and strength) of jump rebids after 1 level and 2 level response) that convey what I have been wanting to show with the 2♣ bid, but a lot more efficiently, allowing room for us to describe our hands at a low level.
Indeed. Broadly speaking, opening 2C is a bad thing for your side. You are a level higher and you haven't started to describe your hand's shape. Aggressive opponents will also see this as an opportunity to take further room away if they can, since they don't have to worry about constructive bidding.
As a result, you should have some idea of where you are heading when you open 2C, and a hand where partner can have some expectation that slam will be on with the right couple of cards. 2C works best when you have a strong one-suited hand, since you get to describe the nature of your hand next round. Two-suited hands are harder, so the hand should be really strong - not just one that will miss game if partner passes the perfect 5 count, but one that is genuinely game-forcing - to make up for what you are giving up with the opening.
Particularly on distributional hands, it's often right to open at the one level even on hands that might qualify for a 2C bid. It's not so likely everyone will pass if some of your strength is in distribution rather than high cards, and if you do get another chance to bid you can be much better off. Strength can be shown later in the auction (assuming there is a later) - distribution can be harder to do so.