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Detroit Tigers vs Boston Red Sox Preview

Detroit Tigers vs Boston Red Sox preview with model projections: Jack Flaherty projected 5.0 K (line 5.5), NRFI probability 55%, 10 mph wind. Full breakdown...

Detroit Tigers at Boston Red Sox MLB game preview for April 20, 2026
DET
Detroit Tigers
Jack Flaherty RHP
@
11:10 AM ET
Fenway Park
BOS
Boston Red Sox
Sonny Gray RHP
Last updated Monday, April 20, 2026
Final This game has finished. Read the recap for final score, model grades, and box score.

Key Facts

Matchup
Detroit Tigers at Boston Red Sox
Date
Monday, April 20, 2026
First Pitch
11:10 AM ET
Venue
Fenway Park
Probable Starters
Jack Flaherty (RHP) vs Sonny Gray (RHP)
Lineups
Confirmed
Odds Snapshot
Apr 20, 11:11 AM ET
Last Updated
Apr 20, 11:09 AM ET

Betting Board

Snapshot Apr 20, 11:11 AM ET
Moneyline
DET +265
BOS -154
Total
Over 7.5 -132
Under 7.5 +100
Run Line
DET +2.5 -148
BOS -2.5 +112

Model Angles

NRFI Model
YRFI · 55%
-2.0% edge
Projected Total
5.6
model combined runs
Park Factor
1.08
Hitter friendly · HR 1.15
First Pitch Weather
48°F
10.1 mph W
The Detroit Tigers visit the Boston Red Sox at 11:10 AM ET at Fenway Park. Probable starters: Jack Flaherty for Detroit Tigers opposite Sonny Gray for Boston Red Sox. Lineups are confirmed. This preview is built deterministically from projected lineups, probable starters, NRFI model context, market prices, first-pitch weather, park factors, and TheCapperIO model context.
  • Starter matchup: Jack Flaherty (Detroit Tigers) vs Sonny Gray (Boston Red Sox).
  • Lineup status: confirmed by both teams.
  • NRFI model: 55% probability, lean YRFI, -2.0% edge.

Pitching Matchup

DET Away
Jack Flaherty
RHP · 0-1 · 5 GS
ERA
3.47
WHIP
1.59
K/9
9.26
IP
23.1
Career: 3.79 ERA · 1.21 WHIP · 10.24 K/9
NRFI: 74.1%
1st Inn ERA: 4.47
BOS Home
Sonny Gray
RHP · 2-1 · 5 GS
ERA
4.30
WHIP
1.30
K/9
5.09
IP
23.0
Career: 3.59 ERA · 1.20 WHIP · 8.99 K/9
NRFI: 80.5%
1st Inn ERA: 3.59

On the season, Jack Flaherty holds the ERA edge in this matchup. Jack Flaherty carries a 3.47 ERA and 1.59 WHIP, while Sonny Gray sits at 4.30 ERA and 1.30 WHIP.
Strikeout rates: Jack Flaherty at 9.26 K/9, Sonny Gray at 5.09 K/9.
K projections: Jack Flaherty at 5.0 (line 5.5)
Sonny Gray projected at 4.7 (line 5.5).
First-inning scoring: Jack Flaherty holds a 74.1% career NRFI rate, Sonny Gray at 80.5%. Combined average: 77.3%.
Both starters throw from the R side, limiting platoon splits for either lineup.

Strikeout Projections

Jack Flaherty vs BOS
Proj: 5.0Line: 5.5
-0.5
Confidence:
Sonny Gray vs DET
Proj: 4.7Line: 5.5
-0.8
Confidence:
View all K projections on SlateIQ

Our strikeout model weighs pitcher K rate, opponent lineup whiff tendency, park factors, and umpire zone size to project total strikeouts per starter.

Jack Flaherty (Detroit Tigers) is projected for 5.0 strikeouts against a posted line of 5.5. The projection is close to the line with no actionable edge.
He faces a moderate-K lineup that strikes out at 22.0% with a 28.0% whiff rate.

Sonny Gray (Boston Red Sox) is projected for 4.7 strikeouts against a posted line of 5.5. The projection is close to the line with no actionable edge.
He faces a moderate-K lineup that strikes out at 22.0% with a 28.0% whiff rate.

The Detroit Tigers lineup is more vulnerable to strikeouts in this matchup. Boston Red Sox batters K at 22.0%, Detroit Tigers batters at 22.0%.

NRFI & First 5 Analysis

NRFI Model
54.9%
probability of YRFI
+-2.0%
market edge
Monitor
Market implied: 56.9%Model: 54.9%
First 5 Innings
3.1est. F5 runs
DET
3.47 ERA
4.6 inn/start
BOS
4.30 ERA
4.6 inn/start
F5 lean: Slight DET
DET K Projection
Jack Flaherty
5.0proj
Line: 5.5
-0.5 NEUTRAL
Confidence
BOS K Projection
Sonny Gray
4.7proj
Line: 5.5
-0.8 NEUTRAL
Confidence
Explore all model projections

Our NRFI model analyzes both starting pitchers' first-inning profiles, the top-of-order hitters in each lineup, the umpire's historical zone, and environmental factors to produce a probability estimate. For this game, the model assigns a 54.9% probability of no runs in the first inning, compared to the market's implied probability of 56.9%.

  • That creates a slim -2.0% edge on YRFI.
  • The best available line is NRFI -132 / YRFI +100 at FanDuel.
  • Home plate umpire Will Little runs a average zone. See the umpire section below for full career data.
  • Our NRFI model sits at 16-22 (42.1%) on official picks this season.

Prop Edges

5 model signals detected
Hits (1+) Strong Hit 0.5
68.1%
Home Run Elite 0.5
16.6%
Home Run Very Strong 0.5
14.6%
Home Run Elite 0.5
16.5%
Roman Anthony
Home Run Strong 0.5
12.4%
See all today's picks and edges

Lineup & Matchup Breakdown

Detroit Tigers Confirmed
K%: 22.0
4Riley GreeneLLF
Whiff rate: 28.0%Team page
Boston Red Sox Confirmed
K%: 22.0
1Roman AnthonyLLF
2Willson ContrerasR1B
3Wilyer AbreuLRF
Whiff rate: 28.0%Team page
Batter vs Pitcher matchup tool

Lineups are confirmed as of this writing.

Detroit Tigers K vulnerability: 22.0% strikeout rate, 28.0% whiff rate.

Boston Red Sox K vulnerability: 22.0% strikeout rate, 28.0% whiff rate.

Ballpark, Weather & Umpire

Fenway Park
Run Factor1.08
HR Factor1.15
Full park profile
Home Plate Umpire
Will Little
Average NRFI: 43.6% 78 games
Full umpire profile
Hourly Game Forecast
48°
11 AM
10 mph
W
48°
12 PM
10 mph
WSW
48°
1 PM
12 mph
W
50°
2 PM
12 mph
W
  • Fenway Park carries a 1.08 run factor (hitter-friendly).
  • Home run factor: 1.15 — the park elevates HR power.
  • Park notes: Green Monster (37ft wall in left field); Pesky's Pole (302ft in right field); Triangle in center field.
  • First pitch forecast: 48F with 10 mph winds from the W. Humidity: 50%.
  • Wind advisory: 10 mph winds from the W may impact fly balls.
  • Home plate umpire: Will Little.
  • Career NRFI rate: 43.6% across 78 games tracked.
  • Zone tendency: Average.
  • K factor: 1.027 (above average strikeouts in his games).

Run Projections & Total

  • Our projection model puts the total at 5.6 combined runs, with Detroit Tigers projected for 2.8 and Boston Red Sox for 2.8.
  • That's 1.9 runs below the posted total of 7.5, suggesting a lean toward the Under.
  • The run projection is essentially a coin flip between these two teams.
The Bottom Line
This is a data-first preview, not a pick. Treat the NRFI model signal as context alongside the pitching matchup. Verify current odds before placing any bet. Bet responsibly. 1-800-GAMBLER.
This preview is generated from thecapper.io projection models and publicly available data. All projections are model estimates, not guarantees. Gamble responsibly. If you or someone you know has a gambling problem, call 1-800-GAMBLER.