I Hate to See

Slams Kicked Away on Such Simple Matters

A
A 7 4 2
Q 8 7 6
Q 10 4 2
9 8 6 4 Q 7
K Q J 6 10 8 5 3
4 3 K 10 9 5 2
A 9 3 8 6
K J 10 5 3 2
9
A J
K J 7 5

In six spades, the only pair in it, this declarer had an opportunity for a top board (one pair was in six clubs). He gets an incredibly lucky break in the spade suit, without which slam is out of the question -- and then threw it away. This hand could go under both this category and finessing, simple elementary lessons that you dismiss as a sophisticated player at some cost.
Opening lead was a heart. Declarer cashed the ace of spades and then ruffed a heart. You now have just one more trump than LHO, which you don't know at this time, with the ace of clubs to be knocked out, so I would point out that you have two other paths to the closed hand. One is the club suit, which does raise the specter of a ruff when you have 8 of them (missing the ace), and the other is the diamond hook, of course.
No one likes to go down at trick 3, but it's not a whole lot worse than going down at trick 12, and there is simply no alternative to the diamond hook eventually. Indeed, I might suggest that going down at trick 3 because the cards aren't right for you is better than going down at trick twelve when the cards were right but you were skeered of going down at trick 3. So there. Take the diamond hook and hope for the best. Now when spades offer that remarkable favor of a queen doubleton, you're in clover. Get out trump and knock out the ace of clubs for a top board.
Here's what happened: ruff a heart at trick 3, king of spades, dropping the queen, jack of spades, 5 of clubs! Was there a miscount? How could there be a miscount when only that remarkable 4-2 split with the queen doubleton saves you? In any event, the queen of clubs held, the ten of clubs was led (this declarer is making sure he goes down), taken by the ace and a heart drove declarer to the same number of trump as his LHO. He wouldn't have been dead yet if he'd preserved the 10 of clubs, but now even if he draws the last trump, he has no way of taking the diamond hook.
However, he led clubs a third and then a fourth time, getting ruffed, and now a heart forced declaer to ruff, cash his ace of diamonds and concede a trick to the king.
Such a simple hand, really, tossed in the ashcan when that extraordinary luck surfaces. Counting also would help: You have six spade winners, three clubs and two red aces for 11. And where can that 12th winner come from? Oh, that is just too obvious to answer.