MLB matchup analysis

Diamondbacks vs Red Sox Prediction, Odds and Model Pick

Wednesday, August 19, 2026 at Fenway Park · 4:10 PM ET

Pass

LyDia decision: Pass on Diamondbacks vs Red Sox

Lab Rating
5.9/10
Model lean
Red Sox 63.8%
Market probability
60.0%
Model edge
+3.8%
Best moneyline
-158
Sportsbooks checked
9
LyDia model
63.8%
Market
60.0%

The case for Boston Red Sox

Bats are hot: +0.043 wOBA
Boston Red Sox is outhitting its own season form over the last 15 days. Recent form is context, not a model input, but it points the same way here.

The case for Arizona Diamondbacks

Their bats are hot: +0.018 wOBA
Arizona Diamondbacks is outhitting its own season form over the last 15 days.

Why it is not official

Setup quality below the bar
Lab Rating is 5.9/10, under the 8.0/10 required for an official pick.
Own bullpen carries risk: 7.1/10
The Boston Red Sox bullpen comes in tired. A lead after six innings is less safe than usual.
Opponent is swinging it
The other lineup is +0.018 wOBA above its season form over the last 15 days.

Why the setup score is what it is

Conviction: 18.05/20
LyDia's win probability for Boston Red Sox (63.8%) is well clear of a coin flip -- this is a real, stated lean, not a guess.
Pitching plan: 6/20
Payton Tolle rates 6 points better than Brandon Pfaadt on LyDia's pitcher score. A real edge, but well short of the gap that earns full credit here.
Bullpen: 8.01/20
LyDia does not see a meaningful bullpen edge for Boston Red Sox here.
Offense: 26.5/40
Boston Red Sox's recent offensive form clearly outpaces Arizona Diamondbacks's over the tracked windows.

Why the price is what it is

Team strength: 51.8%
Before any pitcher or bullpen adjustment, LyDia's team-strength model alone makes Boston Red Sox 51.8% to win. Everything below moves the price from this starting point.
Pitcher score gap: 6 points
The pitcher-score gap favors Boston Red Sox by 6 points. This is the biggest single mover of the price -- a large gap moves it a lot, a small gap barely moves it.
Bullpen adjustment: -0.033
The bullpen-fatigue gap between the two pens nudges the price toward Arizona Diamondbacks. This moves the price less than the starting pitchers do, since a starter covers more of the game than the bullpen.
Net effect: 51.8% -> 63.8%
Team strength alone had Boston Red Sox at 51.8%. After the pitcher and bullpen terms, the price is 63.8% -- the same number shown as Model Lean above.
The verdict LyDia passes. The combined Lab Rating did not clear the official threshold.
Read the full model output

The combined Lab Rating did not clear the official threshold.

Game information

MatchupArizona Diamondbacks at Boston Red Sox
DateWednesday, August 19, 2026
First pitch4:10 PM ET
VenueFenway Park
Starting pitchersBrandon Pfaadt vs Payton Tolle
WeatherGame-time forecast: 88°F, 0% precipitation chance, 12 mph wind from W.

Starting pitcher matchup

Full Pitcher Matchup Tool →
Brandon PfaadtDiamondbacks · RHP
vs
Payton TolleRed Sox · LHP
MetricDiamondbacksRed Sox
Pitching planTraditional starterTraditional starter
Expected innings65⅔
ThrowsRL
LyDia pitcher score (higher is better)7278
ERA (lower is better)3.112.97
WHIP (lower is better)1.131.06
K/9 (higher is better)5.910.0
K-BB% (higher is better)9.8%21.0%
K% (higher is better)16.1%27.8%
BB% (lower is better)6.3%6.7%
BB/9 (lower is better)2.32.4
HR/9 (lower is better)0.81.0
Ground-ball rate50.7%37.5%
Fly-ball rate49.3%62.5%

Pitcher edge: LyDia gives Payton Tolle a 6-point edge over Brandon Pfaadt, driven mainly by K/9 (10.0 vs 5.9) and K-BB% (21.0% vs 9.8%).

How to read this: the scorecards above name the starters; every number lives in this table. Highlighted cells mark a gap big enough to matter. K% and BB% are strikeout and walk rate as a share of batters faced -- K-BB% is the two combined into one skill number. HR/9 is home runs allowed per nine innings. Ground-ball and fly-ball rate are neither good nor bad on their own: high ground-ball pitchers trade strikeouts for double plays and fewer home runs, and on this data source the two rates are complementary (they add to 100%), not independent reads.

Strikeout Projections Full strikeout projections →

Brandon Pfaadt strikeouts
3.1 LyDia projected Ks
No K play · -0.4K difference is below LyDia's 0.7K threshold
Market 3.5K · O -113 / U -110 · 5 books
Payton Tolle strikeouts
5.0 LyDia projected Ks
No K play · -0.5K difference is below LyDia's 0.7K threshold
Market 5.5K · O -115 / U +103 · 5 books

Same data source as the Pitcher Matchup Tool, where every starter on the slate is compared side by side.

Neither side is playing well. Diamondbacks are 4-6 in their last 10, averaging 4.2 runs per game over the last 15 days, and swinging above their season form; Red Sox are 4-6 in their last 10, averaging 6.3 runs per game over the last 15 days, and swinging above their season form. On the season Red Sox carry the better run differential per game (+0.76 against +0.02).

MetricDiamondbacksRed Sox
Last 104-64-6
Last 10 by venue (away team on the road, home team at home)6-4 on the road7-3 at home
OPS, last 15 days0.7620.840
wOBA, last 15 days (hot/cold read)0.3320.364
Runs per game, last 15 days4.26.3
K% last 15 days (lower is better)19.1%17.8%

Last 15 days only. Hot and cold streaks for all 30 teams live on the Stats page.

30-day offense

Full offense tool →
Last 30 daysDiamondbacksRed Sox
OPS0.773 (+0.061 vs szn)0.792 (+0.064 vs szn)
Runs per game4.96 (+0.460 vs szn)5.57 (+1.056 vs szn)
wOBA (model offense input)0.339 (+0.024 vs szn)0.346 (+0.025 vs szn)
K% (lower is better)18.1% (-1.2% vs szn)20.3% (-1.2% vs szn)

Over the last 30 days the Red Sox have been the better offense, 0.346 wOBA to 0.339. They are running hot against their own season line (+0.025 wOBA).

Season profile

Full Stats page →
MetricDiamondbacksRed Sox
Record66-6168-58
Run differential / game (team quality)+0.02+0.76
Runs scored / game (offense, season)4.504.52
Runs allowed / game (defense, season, lower better)4.483.75
Season OPS0.7120.728
K% season (lower is better)19.3%21.5%
OPS vs opposing hand (season)0.7830.715

Season-long team quality, not recent form. Run differential and run environment come from the season standings; splits for all 30 teams live on the Stats page, including the run environment table.

Every team on today's slate, on any two axes you pick. Diamondbacks and Red Sox are highlighted.

Diamondbacks
Combined risk
6.0 Normal
Fatigue
5.4 Normal
Efficiency
3.9 Below average
Red Sox
Combined risk
7.1 Tired
Fatigue
7.7 Tired
Efficiency
6.2 Effective

Risk is what the model actually uses: fatigue blended with how well the pen has pitched. High fatigue with high efficiency is a tired pen that is still getting outs.

MetricDiamondbacksRed Sox
Fatigue5.4/10, Normal7.7/10, Tired
Efficiency3.9/10, Below average6.2/10, Effective
Combined risk6.0/10, Normal7.1/10, Tired
Relief innings, last 7 days20.326.7
Back-to-back arms35
7-day ERA5.753.04
7-day WHIP1.430.98

Fatigue measures workload. Efficiency measures recent run prevention. Combined risk is what the moneyline and totals systems use.

Run total projection

Full Totals Projections →
LyDia projection
8.3
Market total
8.0
Projected away runs
3.1
Projected home runs
5.2
Over price
-105
Under price
-105
Arizona Diamondbacks team total
3.1 projected
Line 3.5 · O -109 / U +105
No team-total lean
Boston Red Sox team total
5.2 projected
Line 4.5 · O +107 / U -124
Over research lean (+0.7)

The model and market are close. Team totals remain research-only until their graded sample is established.

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