What's at stake

Whether the Mets and Diamondbacks combine for more than specific totals — 3.5, 5.5, 6.5, 8.5, or 9.5 runs — determines each Over/Under market.

Each separate market settles on the game's official final combined run total under the site's rules, so innings, weather-shortened games, and official scoring matter.

Who's in play

The New York Mets and the Arizona Diamondbacks supply the hitters, pitchers, and managers whose actions set the final run total.

Probable starters, each club's lineup spots (power vs. contact), and bullpen arms — plus managers' matchup decisions and the umpire crew — directly affect scoring outcomes.

What drives it

Starting pitchers' quality, pitch counts, and early-inning matchups drive the biggest swings in total runs.

Park factors, wind and temperature, handedness splits, base-running aggressiveness, and bullpen depth all shift the probability of clearing different Over/Under lines.

What to watch

Projected starters and official lineups, typically posted about an hour before first pitch, are the first decisive signals.

Also monitor weather updates, first-inning scoring, early pitch counts, bullpen usage patterns, and any late scratches or injuries; those in-game developments change the odds for each line.