The Truth about Pluribus Poker AI Donk Bets

Much has been said in the press about Pluribus Poker AI donk bets. In their press release, Facebook says “ Pluribus disagrees with the folk wisdom that donk betting (starting a round by betting when one ended the previous betting round with a call) is a mistake; Pluribus does this far more often than professional humans do. ” So is it the case, how much, and in what specific context ?

Carnegie Mellon University published 10K hands played by Pluribus against the pros. So we can have a deep look at donk betting by Pluribus, but also by the pros. I’ll focus only on single raised pots, ie when there is only an open and a call preflop and no reraise/3bets. 3bet pots have a very different dynamic and there are less of them to look at.

As a reminder a donk bet is a bet where the preflop defender (player who just called) is out of position and leads the betting on the flop. This has traditionally been considered as bad play, hence the name “donk”.

Pluribus was in a position to donk bet 568 times and did it 11 times, so 1.9%. This is twice as much as the pros who did 1% of the times they had the opportunity to, but not huge either. Let’s look at every single one:

Every Pluribus Donk Bet in SRP

  • Strikingly, Pluribus has only donk bet in multiway pots. Interestingly Thomas Pinnock does mention multiway pots as one spot where donk bets “could” make sense as there is less a need to protect the checking range. This is because every player will need to be less agressive on the flop with lower equity.
  • If we’re donk betting, we need to protect that range. Pluribus here does 5 bets with very strong hands and 5 “bluffs” so it looks pretty balanced.
  • Maybe we can use this in live games that have many multiway pots with a decent frequency of value to bluff. We can’t go crazy on frequency, but Pluribus does it almost at 10% frequency (donk on multiway pots).
  • As with c betting, Pluribus varies bet sizes including some overbets.

3 thoughts on “The Truth about Pluribus Poker AI Donk Bets”

  1. I have always liked so-called “donk” betting in these particular situations, and I am sure I do it even more than Pluribus.

    If the second player likes to follow standard strategy, which most do, then his check-calls or in position calls against the preflop raiser (not to mention raises) protect your checks out of the the big or small blind against excessive continuation betting.

    Moreover, there are so many good reasons to bet here:

    –It maximizes the value of hands like bottom pair and gut shot straight draws to give both players a chance to fold if they missed or a decision with lots of marginal hands that are splitting the pot equity with you. (If they call, you get information and can win a big pot with a concealed hand if the right turn card comes.) You protect a fragile made hand or win with low cards and a marginal draw.

    –Conversely, with a set or two pair it gives you the chance to bet three streets when your opponents hit, or to get raised and stack an overpair, top pair or drawing hand.

    –Finally, with a strong drawing hand like a flush and a straight draw, or an open-ended straight draw plus overcard(s) and a backdoor flush draw, it lets you barrel three streets with something like six or eight high on a semi-bluff. This gives you lots of equity without hitting your hand, balances your three streets of value with two pair plus, and wins a lot when you make your draw too.

    I remember a hand I played years ago where five players took the pot in a raised hand. I hit a set of sixes from the big-blind, pushed much deeper than twice the pot, and got called by AK or AQ with top pair top kicker. People couldn’t believe I played it that way. One player folded 98 on the 76 board and another folded the flush draw with JTs or QTs.

    How could you play it that way, they said? That’s exactly why I did. I forced two great drawing hands to fold who would have pot odds to call (one of which would have hit), and got called for a mint by a hand that was next to dead.

    1. If you lead out here, I believe you shouldn’t have a check-raising range on the flop. You have a leading range with your best hands and many draws and small made hands, and you have a check calling range with good but not great hands and draws.

      1. Against this strategy, the initial raiser should triple barrel bluff more often, but you will be calling down three times with your best top-pair hand in your PF calling range, and any time you improve to two pair or a set from top or middle pair on the turn, and any time you hit something like a bottom end open-ended straight draw or a king through jack flush draw. Plus, as mentioned, if they continuation bet too much on the flop the other caller will kill them. This strategy is most vulnerable when they adjust not by flop continuation betting much more, but by second and third barrelling against your calls more. But it’s gutsy to do and is still high variance bc you are calling down three bets on lots of runouts with a strong top pair or improved two pair.

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