MLB playbook

A pitcher-driven daily market, and what to check first · 8 min read

Baseball is a game of small edges and a lot of noise: each team plays 162 regular-season games, and even a 100-win team loses 62 of them. This playbook is the MLB layer on top of Levels 1 to 3. Much of the NHL playbook carries over: a moneyline-led market, a spread fixed at 1.5, and one player whose status moves the price.

How the MLB market works

Opening lines usually go up the day before a game, and the price firms up as starters are confirmed, lineups come out and money arrives (see What happens to a line until kickoff; for baseball, read first pitch).

• The moneyline leads. Most baseball betting is on the moneyline, and the run line is priced around it. Prices are quoted in cents: a favorite at −150 with the underdog at +140 is a 10-cent line, or dime line, and at similar prices, the wider the gap between them, the more the book keeps (The vig).
• One game says little. Even a fair −200 favorite, a two-in-three chance, loses one game in three. Losing runs are normal at good prices, so judge a long run of bets by closing line value, not a week of results.

The starting pitcher

In hockey the goalie is the news; in baseball it is the starting pitcher. The gap between a team's best and worst starters is often the biggest swing in its price from one day to the next.

• Listed pitchers or action. A named starter can be scratched late. A listed-pitchers bet stands only if both named starters start; otherwise it is void and your stake comes back. An action bet stands whoever starts: some books re-price it to the new line, others keep your original price. Defaults differ by book, and some let you choose. A named pitcher usually only has to throw the first pitch to count as starting. This is baseball's main settlement trap, so read the house rules before you bet.
• Openers and bullpen games. Some teams start a reliever for an inning or two before a longer-lasting pitcher takes over, or use relievers all game. The listed starter then says little about who pitches most of the innings.

Once a scratch reaches your phone, it is usually in the price; the edge is in judging pitchers better than the market or reading a move early (Why lines move).

Bullpens

Starters rarely pitch deep into games anymore, so relievers often throw a third or more of the innings, and many games are decided late. A bullpen is not the same every night: relievers who pitched the last two or three days may be unavailable or less sharp, which pushes late innings to weaker arms. The market watches workload too.

The run line

The run line is almost always 1.5 runs and, like the puck line, is priced like a moneyline: the favorite at −1.5 usually pays plus money. The favorite must win by two, and more than a quarter of games are decided by a single run. The baseball quirk is the home favorite's last at-bat. A home team leading after the top of the ninth doesn't bat again, and one that wins in its last at-bat, in the ninth or extra innings, nearly always wins by one, because the game ends when the winning run scores; only a walk-off home run counts all its runs. The road team always gets its full turn. So a home favorite covers −1.5 less often than a road favorite with the same chance to win. Books price this; hold each run line to its own fair chance, never the moneyline's, as in the NHL playbook's example.

First five innings

First five innings (F5) bets settle on the score after five innings, so they lean on the starters and leave out most of the bullpen. F5 suits a view on a starter but not his bullpen.

• Ties. Games are often tied after five. A three-way F5 line makes the tie its own result, a two-way line usually makes it a push, and the F5 −0.5 run line loses on it. Hold each to its own break-even.
• Short games. If a game stops before five full innings, F5 bets are usually void. A full-game moneyline can stand on a rain-shortened game once it is official, while full-game run lines and over/unders often need nine innings, or eight and a half if the home team leads. Full-game over/unders count extra innings, so a game tied after nine adds at least one run. Rules vary by book.

Over/unders

A baseball over/under starts with the starters and bullpens. Then:

• The park. Park factors differ widely, from thin air in Denver to fences and foul ground. They are well known and priced, so ask how today differs from the park's normal.
• Weather. Wind matters most at open parks where it blows hard; Chicago's Wrigley Field is the famous case. Warm air helps the ball carry and cold air holds it back; a closed roof takes weather out.
• Umpires. Plate umpires' strike zones differ a little; the effect is small, noisy and widely tracked: a tiebreaker at most.
• The price moves more than the number. As in hockey, books often hold a number like 8.5 and move the price first. The fewer runs expected, the more often games land exactly on the number, so a half-run matters more on a low line than a high one. Value it by games lined near that number, not by an all-games average (Key numbers explains the idea).

Lineups and platoon splits

Lineups usually come out a few hours before first pitch. Regulars sit now and then, for example in a day game after a night game, and catchers rest most; one missing bat usually moves a line less than a pitcher change, but several add up. Platoon splits matter too: most hitters do better against pitchers who throw with the opposite hand, so a lineup full of left-handed hitters can be noticeably weaker against a left-handed starter.

Underlying numbers and results

ERA counts earned runs, and those depend on more than the pitcher: the defense and bullpen behind him, where balls in play happen to land, and how hits bunch together. Over a few starts that noise is large. Steadier signs of skill are strikeouts, walks, whiff rate and the quality of contact he allows (barrel rate allowed), all rolled into xwOBA. A pitcher whose ERA is far better than those numbers tends to give some of it back, and one whose ERA is far worse tends to improve. The market reads them too; knowing them keeps you from paying for a hot streak.

Props and same-game parlays

A strikeout prop leans on the pitcher's whiff rate, the opposing lineup's strikeout habits and how long the manager lets him pitch. Props carry more hold and lower limits than the moneyline. Same-game parlays stack correlated legs, like a starter's strikeouts and the under, and the book prices that in and holds far more than on a single bet. Read the parlays lesson first, and stake any parlay smaller than a single bet.

A pre-bet checklist

1. Who is pitching, and how does your bet settle if that changes?
2. Is it an opener or a bullpen game, and how tired is each bullpen?
3. Moneyline, run line or F5? Compare each bet's fair chance with its own break-even, never another's.
4. Over/under? Check the park, wind, temperature and roof.
5. Are the lineups out? If not, you are betting on them too.
6. Have you shopped the price? Compare books first (Line shopping).
7. Is the stake small? One shared misread, like a wrong read of a pitcher behind several bets, can sink a few at once, so size for a bad week (Variance and drawdowns).

How Consensus Edge helps

We compare prices across many sportsbooks and remove the vig, so you can see what the market really thinks and where the best price is. We blend Square (the books), Sharp (our models) and Crowd (prediction markets) into one chance, and we re-price regularly until first pitch, so line moves after pitcher and lineup news reach our numbers, though right after news any board, ours included, can trail the books. Each bet shows BET, LEAN or NO EDGE; BET and LEAN carry a small suggested stake, and we publish how our picks did against the close. NO EDGE is not a grade: it means a fair price, or a market we don't grade. Start on the slate or read how it works, and bet only what you can afford to lose.

Terms in this playbook

Opening LineMoneylineRun LineFirst 5 InningsPushBreak-evenOver/UnderPark FactorPlatoon SplitsWhiff RatexwOBABarrel RateHoldSame-Game ParlayCorrelationSquareSharpCrowdBETLEANNO EDGE