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St. Louis Cardinals vs Miami Marlins Preview

St. Louis Cardinals vs Miami Marlins preview with model projections: Dustin May projected 4.5 K (line 4.5), NRFI probability 44%. Full breakdown inside

St. Louis Cardinals at Miami Marlins MLB game preview for April 21, 2026
STL
St. Louis Cardinals
Dustin May RHP
@
6:40 PM ET
loanDepot park
MIA
Miami Marlins
Chris Paddack RHP
Last updated Tuesday, April 21, 2026
Final This game has finished. Read the recap for final score, model grades, and box score.

Key Facts

Matchup
St. Louis Cardinals at Miami Marlins
Date
Tuesday, April 21, 2026
First Pitch
6:40 PM ET
Venue
loanDepot park
Probable Starters
Dustin May (RHP) vs Chris Paddack (RHP)
Lineups
Projected
Odds Snapshot
Apr 21, 6:41 PM ET
Last Updated
Apr 21, 11:16 AM ET

Betting Board

Snapshot Apr 21, 6:41 PM ET
Moneyline
STL +109
MIA -116
Total
Over 8.5 -120
Under 8.5 -102
Run Line
STL -1.5 +158
MIA +1.5 -192

Model Angles

NRFI Model
YRFI · 44%
-10.2% edge
Projected Total
2.3
model combined runs
Park Factor
0.94
Pitcher friendly · HR 0.90
First Pitch Weather
Roof
Climate controlled
The St. Louis Cardinals visit the Miami Marlins at 6:40 PM ET at loanDepot park. Probable starters: Dustin May for St. Louis Cardinals opposite Chris Paddack for Miami Marlins. Lineups are projected until first pitch. This preview is built deterministically from projected lineups, probable starters, NRFI model context, market prices, a roofed ballpark note, park factors, and TheCapperIO model context.
  • Starter matchup: Dustin May (St. Louis Cardinals) vs Chris Paddack (Miami Marlins).
  • Lineup status: projected until official release.
  • NRFI model: 44% probability, lean YRFI, -10.2% edge.

Pitching Matchup

STL Away
Dustin May
RHP · 2-2 · 4 GS
ERA
6.98
WHIP
1.60
K/9
6.98
IP
19.1
Career: 4.04 ERA · 1.22 WHIP · 8.18 K/9
NRFI: 66.1%
1st Inn ERA: 5.44
MIA Home
Chris Paddack
RHP · 0-3 · 3 GS
ERA
5.59
WHIP
1.45
K/9
8.38
IP
19.1
Career: 4.67 ERA · 1.22 WHIP · 8.19 K/9
NRFI: 62.3%
1st Inn ERA: 6.46

On the season, Chris Paddack holds the ERA edge in this matchup. Dustin May carries a 6.98 ERA and 1.60 WHIP, while Chris Paddack sits at 5.59 ERA and 1.45 WHIP.
Strikeout rates: Dustin May at 6.98 K/9, Chris Paddack at 8.38 K/9.
K projections: Dustin May at 4.5 (line 4.5)
Chris Paddack projected at 4.5 (line 4.5).
First-inning scoring: Dustin May holds a 66.1% career NRFI rate, Chris Paddack at 62.3%. Combined average: 64.2%.
Both starters throw from the R side, limiting platoon splits for either lineup.

Strikeout Projections

Dustin May vs MIA
Proj: 4.5Line: 4.5
0.0
Confidence:
Chris Paddack vs STL
Proj: 4.5Line: 4.5
0.0
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.

Dustin May (St. Louis Cardinals) is projected for 4.5 strikeouts against a posted line of 4.5. 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.

Chris Paddack (Miami Marlins) is projected for 4.5 strikeouts against a posted line of 4.5. 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 St. Louis Cardinals lineup is more vulnerable to strikeouts in this matchup. Miami Marlins batters K at 22.0%, St. Louis Cardinals batters at 22.0%.

NRFI & First 5 Analysis

NRFI Model
44.4%
probability of YRFI
+-10.2%
market edge
Monitor
Market implied: 54.5%Model: 44.4%
First 5 Innings
1.3est. F5 runs
STL
6.98 ERA
4.8 inn/start
MIA
5.59 ERA
6.4 inn/start
F5 lean: Moderate MIA
STL K Projection
Dustin May
4.5proj
Line: 4.5
0.0 NEUTRAL
Confidence
MIA K Projection
Chris Paddack
4.5proj
Line: 4.5
0.0 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 44.4% probability of no runs in the first inning, compared to the market's implied probability of 54.5%.

  • That creates a slim -10.2% edge on YRFI.
  • The best available line is NRFI -120 / YRFI -102 at FanDuel.
  • Home plate umpire Manny Gonzalez runs a tight zone. See the umpire section below for full career data.
  • Our NRFI model sits at 17-23 (42.5%) on official picks this season.

Prop Edges

2 model signals detected
Hits (1+) Lean Hit 0.5
67.4%
Home Run Elite 0.5
16.4%
See all today's picks and edges

Lineup & Matchup Breakdown

St. Louis Cardinals Projected
K%: 22.0
1Nolan GormanL2B
Whiff rate: 28.0%Team page
Miami Marlins Projected
Projected batting order unavailable. This will update when probable or confirmed lineup data is available.
Batter vs Pitcher matchup tool

Lineups are projected as of this writing.

St. Louis Cardinals K vulnerability: 22.0% strikeout rate, 28.0% whiff rate.

Ballpark, Weather & Umpire

loanDepot park
Run Factor0.94
HR Factor0.90
Full park profile
Home Plate Umpire
Manny Gonzalez
Slightly tight NRFI: 53.6% 84 games
Full umpire profile
  • loanDepot park carries a 0.94 run factor (pitcher-friendly).
  • Home run factor: 0.90 — the park suppresses HR power.
  • Park notes: Extreme pitcher-friendly; Retractable roof; Suppresses HRs significantly.
  • Roof: Retractable.

Climate controlled. Roof expected closed. Standard 72F conditions, no wind factor.

  • Home plate umpire: Manny Gonzalez.
  • Career NRFI rate: 53.6% across 84 games tracked.
  • Zone tendency: Slightly tight.
  • K factor: 0.948 (below average strikeouts in his games).

Run Projections & Total

  • Our projection model puts the total at 2.3 combined runs, with St. Louis Cardinals projected for 2.3 and Miami Marlins for 0.0.
  • That's 6.2 runs below the posted total of 8.5, suggesting a lean toward the Under.
  • The run projection favors St. Louis Cardinals by 2.3 runs.
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. Confirm lineups at first pitch. 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.