Boston Red Sox at Arizona Diamondbacks, MLB forecast
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Win probability
Starts from the pregame forecast, then moves with the score and the time left after each inning. Above the line favors ARI.
Game center
From the ESPN box score.
Top performers
Red Sox- Masataka YoshidaBatting1-4, 1 RBI
- Lucas GiolitoPitching5.0 IP, 2 ER, 2 K
Diamondbacks- James McCannBatting3-4
- Brandon PfaadtPitching6.0 IP, 1 ER, 7 K
Scoring summary
- 7Alexander hit sacrifice fly to center, Marte scored, Carroll to third.1–5
- 4McCarthy singled to left, McCann scored, Locklear to second.1–4
- 3Yoshida singled to center, Eaton scored.1–3
- 2Perdomo hit sacrifice fly to right, Locklear scored.0–3
- 2McCarthy grounded into fielder's choice to shortstop, Del Castillo scored and McCann scored on error, Locklear safe at third on fielding error by shortstop Story, McCarthy to second.0–2
The pick
Reconstructed from what was known before the game: the ratings at that point and the closing line.
Red Sox 53%
Forecast Elo ratings alone
How often that comes true: MLB favorites the forecast gave 50–55% have won 52.7% of 2,871 graded games.
- Market
- BOS 53%
- ML BOS -125 / ARI +105
- Pre-line forecast
- BOS 53%
- Elo + market-implied
- Elo ratings
- BOS 51%
- Ratings vs. market
- −1.8 pts
- BOS: Elo 51.4%, market 53.2%
- Fair odds
- BOS -114
- ARI +114 · the forecast as odds, no margin
- Pregame projection
- BOS 4.4 – 4.1 ARI
- Margin from the forecast, posted total 8.5
How the number is built
Elo inputs in rating points (higher favors that team; 25–28 Elo is about a point of spread in football and basketball), then how the pieces combine.
| Factor | BOS | ARI | Why |
|---|---|---|---|
| Team rating | 1528 | 1516 | Elo entering the game; 1500 is league average |
| Home field | — | +18 | Worth 18 Elo in MLB |
| Starting pitchers | +11 | −6 | BOS: Lucas Giolito: team allows 0.53 fewer runs than with its usual starter (≈10 weighted starts) · ARI: Brandon Pfaadt: team allows 0.30 more runs than with its usual starter (≈10 weighted starts) |
| Elo ratings | BOS +10 Elo | BOS 51.4% | |
| Market-implied ratings | BOS 53.7% | Team strength as past closing lines priced it, same game context | |
| Pre-line forecast | BOS 53.4% | 15% Elo, 85% market-implied (log-odds blend) | |
| Forecast | BOS 53.2% | Follows the market (vig removed): in testing, adding the ratings made it less accurate | |
Tale of the tape
This season coming into the game, regular season, each number with its league rank (the longer the bar, the higher). Home and road: the host's record at home against the visitor's on the road. Opponent Elo: how strong the teams each has played are, 1st the toughest.
| BOS | Stat | ARI |
|---|---|---|
| 6th of 304.9 | Runs scored | 4.95th of 30 |
| 13th of 304.3 | Runs allowed | 4.823rd of 30 |
| 5th of 30+0.7 | Margin | +0.215th of 30 |
| 7th of 306–4 | Last 10 | 7–32nd of 30 |
| 11th of 3034–36 | Road vs home | 37–3318th of 30 |
| 14th of 301501 | Opponent Elo | 149625th of 30 |
| 6th of 301528 | Elo rating | 151611th of 30 |
Rating history
Each team's Elo over the last two seasons. Hover or drag to compare on any date.
Recent form
Last five results, and whether the forecast hit.
Against the line
How each team has done against the closing spread and total, coming into this game.
| This season |  BOS |  ARI |
|---|---|---|
| Run line | 74–68 | 74–68 |
| Last 10 | 4–6 | 9–1 |
| Favorite | 36–49 | 32–46 |
| Underdog | 38–19 | 42–22 |
| Overs–unders | 72–70 | 72–70 |
| Overs–unders, last 10 | 5–5 | 4–6 |
Against each game's closing line. Books set every line knowing these records: across 3,901 past games, the team with the better record against the spread so far that season covered 51.2%, short of the 52.4% a standard −110 bet needs, and over/under streaks held 48.0% of the time. They describe the past.
Head to head
BOS 2–5 ARI in their last 7 meetings; the forecast called 1 of 7.