I have observed that professional poker hands (in hold 'em, at least) almost never have multi-way showdowns (3 or more players remaining after the final betting round). This is in stark contrast with some very casual games I have been in.

I presume that beginner players often check until they have a good hand, rather than account for the possibility of improving on later streets. More experienced players will correctly bet with a hand that needs to improve or fold with a good hand that they realise is beat. Further, they place much more importance on position and will be more likely to fold when out of position (because it is harder to predict your pot odds when others may re-raise within the same betting round).

Two questions:

1. Does anyone have an empirical guess of the percentage of professionally played no-limit hold 'em hands that have a multi-way showdown?

2. Have I missed other important reasons that explain why they are so rare?

Thanks-

They're rare because casuals will play more hands and carry on with more marginal hands. A good player will fold junk quicker and recognise when they're drawing close to dead, which happens more often when you're up against multiple opponents

1) No.

2) Your reasoning is completely wrong. Sixfour's post is closer to correct here -- in multiway spots there are more opponents who can have a good hand, so you need a better hand to call down with. Weaker players will likely put in too much money with hands like gutshots and middle pairs, while stronger players will correctly find folds with these hands multiway.

Pro players know how to fold preflop. Most recreationals lack the discipline to fold 3/4 hands preflop.

If every player at the table is using a standard preflop strategy, as you'd find on any modern chart, then only a tiny fraction of pots will see a multiway flop, nevermind a multiway river.

So what your question really boils down to, is "why are there so few multiway flops when following modern preflop strategy?".

The answer to that question is a bit more complicated than whales being whales.

I guess multiway pots have a lot more actions from which you can draw information. Skilled poker players are already able to draw very robust conclusions from the actions playing against one other player. With the interaction of 3 players that amount of information is vastly bigger (and people tend to play more straightforward with more people in the pot as bluffs become less likely to succeed)
So you will see skilled players holding the weakest hand able to fold before showdown.

This is the biggest factor IMO. When you routinely have 3, 4, 5 way flops vs. 0 or 1 way flops, it's way more likely that you'll see a multiway showdown.

this sounds interesting

Folding after a 1-way flop is the new meta.

LOL, I meant zero or two.

Imagine a game where everyone’s hole cards are exposed and a flop is dealt. Who should bet and who should call a bet in such a game? Obviously the player with the best hand should continue. Depending on the bet sizing and pot size, the player with the best draw likely might be able to profitably call. Everyone else will likely not be able to continue profitably.

Obviously that’s not a realistic game, but better players are able to more accurately assess whether they are in the “best hand”, “best draw”, or neither category. The “neither” category almost always should be folding prior to showdown. Since there’s only one best hand and one best draw, most hands among good players will wind up heads up.

This is completely wrong ^

The entire concept of bluffing means not having the best hand, often not having the best draw, and betting anyway to represent that you do.

The metaphor stands. Sharper players will narrow ranges more quickly, which draws comparisons to playing more face up. If you're playing a face up 9-way flop, you're bound to see far fewer multiway showdowns.

I still think preflop is the biggest factor though.

This is an oversimplified view of bluffing.
-You gain EV from folding out equity that's already ahead or might outdraw you (fold equity from folding out worse hands before the river is a thing)
-You also gain EV from the implied odds when the bluff fails you outdraw them.

It also doesn't really have anything to do with Stremba's point.

Absolutely disagree.

These are both true, but the main driver of bluff ev (at least with pure bluff combos) is from folding out our opponent's equity share, which only happens...because our bluffs represent us having a good hand. If we played a cards up game of poker, bluffs with the purpose of equity denial would never work. Of course, we would still deny some equity when we bet a bluff and our opponent has a worse hand than our bluff and folds anyway.

No, it absolutely has to do with Stremba's point. Stremba's (seemingly intended) point is that good players can realize when they have the best hand or a strong enough draw to continue, and can avoid putting money in in other situations.

My counterpoint is that good poker players relatively frequently put money into the pot even if they 1) think it's very unlikely they have the best hand and 2) don't have a good draw. That is, good players will regularly bet in Stremba's third "neither" category, and will regularly use "neither" category hands as triple barrel bluffs.

So my main contention is that bluffing is a complete counterpoint to Stremba's view that good players only put money into pots with hands that are 1) likely to be the best or 2) likely to become the best. Good players will bluff with plenty of hands where both of these don't apply, and that's part of a solid and balanced strategy, and I think this really invalidates Stremba's whole post.

I'm a bit curious why you think it's an irrelevant point though?

I think he was just trying to illustrate the idea that pro players can more quickly and accurately narrow their ranges, rather than trying to hard-solve face up poker.

“best hand”, “best draw”, or neither category - is wildly oversimplified and incomplete. Obviously bluffing with trash is valid, and would never work face up. So I understand where you're coming from.

Aggression is favored for most preflop situations in theory. Preflop someone will open, and only the BB has a large incentive to have a significant calling range. You can have flats but most positions mostly 3-bet or fold. This already makes it hard to have multi-way pots since you need a very strong hand to continue cold vs. a 3-bet. Even vs. a raise and a call the third player needs a pretty strong range to continue as well and will usually continue as a 3-bet.

op, you're seeing survivorship bias in action

your friends in the friendly game can play that way because everyone sucks so they don't go broke

if they go play at a casino vs better players, they'll go broke quickly

but yes like others have said

bad players are there to play cards and have fun, they are not incentivized to fold even when they are aware how bad their chance of winning is

good players aren't there to play cards but win money and that means folding out your bad hands instead of dumping money seeing flops and folding easier

when i have bottom pair in a multi way pot i'm folding to any reasonable sized raise while a recreational player will call to see if they can improve their hand or not even thinking about what others have, just think "nice i got a piece of it"