gab7nt

1D 2D 3H(splinter) 4NT... It would surprise me if anyone missed this grand.

"The" requirements for notrump overcalls are real, whether you believe them or not. I am surprised by the pride you seem to take in your lack of understanding of elementary bidding.

The requirements for a 1NT overcall are different depending on position. In fact, the requirements for a 1NT opening bid is also different from that of a 1NT overcall. Let's say you play 15-17 notrump. No matter what your opening NT range is, direct seat 1NT overcall is 15.5 - 18.25. When both opponents have bid a 1NT overcall is 16.75-19.00

What makes you so sure opponents have a fit?

You are one point shy of a 1NT bid. I would not bid it but there are only a few of us solid citizens left. My guess is most would bid 1NT. The sad thing is that there are probably very few players who even realize the hand is not good enough for a 1NT call.

You have forgotten the early part of the auction: namely you did not overcall 1S, you passed. Therefore, 2S here cannot be a great hand with spades... if so why did you not overcall initially? 2S here clearly shows a hand that wants to compete in clubs but with an added feature: a semi decent five-card spade suit.

At the point RHO bids 2D why on earth would you be thinking about competing with 4s over 4H or 5S over 5D? What gives you the impression the opponents have game? What gives you the impression it is opponents hand rather than ours? Why do you think it's OK to mastermind the auction? How about doing it the right way: Describe your hand and COOPERATE with partner and TOGETHER decide on the right way to procede.

West should have bid 2S over 2D. By passing then, he made his bed. He did not involve partner and has zero right to double 5D. Passing 2D was a bigger error than doubling 5D.