Mack Meller is North America's best Scrabble player and has a very instructive YouTube channel. On that channel, he has just finished a 100-game match against the current strongest Scrabble bot, aptly called BestBot. That match went to BestBot with 58 - 42 wins.

Mack has just announced a rematch (https://www.youtube.com/watch?v=x_DgVkIWc_4).

In the first match, Mack scored 408 points on average and BestBot scored 434.

The bot has the following capabilities (not changed significantly since the first match):

• It knows all the words in the Scrabble dictionary

• It has precomputed values for how good every combination of letters is

• It simulates the next moves of the game in advance through a Monte Carlo process to determine its top play

• It can perfecly calculate the best possible sequence of play in the endgame, when both players know which tiles the opponent still has

• It can similarly calculate some pre-endgame situations fully, although its 3-minute time limit per move might be to short to finish the calculation

The bot does not:

• Play invalid words as a bluff

• Explicitly take context into account (such as "is an S worth more on this particular board than usual") - this only happens implicitly through the Monte Carlo approach

• Infer what tiles its opponent is likely to be holding from their previous moves

• EDIT: ...take into account very low-scoring moves (only the 40 best candidate moves are looked at more closely; this is almost always enough to identify the best move in the position, but can miss some unusual, sneaky low-scoring plays)

The match is played to a 20-minute time control and North American challenge rules (playing an invalid move means you lose your turn; Mack cannot look up whether a word is valid during the game).

Resolution criteria:

• If the match ends 50 - 50, spread is the tiebreaker unless Mack decides to play a 101st game to break the tie, in which case that counts

• If the match ends 42 - 58 (same score as last time), resolves to "Mack doesn't to better than last time" regardless of spread

• If Mack doesn't finish the series by EOY 2025 for whichever reason, resolves NA

• The bot getting any significant upgrade while the match is ongoing doesn't affect this market