MLB matchup analysis
Athletics vs Diamondbacks Prediction, Odds and Model Pick
Tuesday, July 21, 2026 at Chase Field · 9:40 PM ET
LyDia prediction: Arizona Diamondbacks moneyline
The case for Arizona Diamondbacks
Why it is not official
Read the full model output
Arizona Diamondbacks remains on the watchlist. Lab Rating 6.7/10: model edge 35, pitcher 10, bullpen 2.11, market 15, base 5. LyDia projects 75.4% against a 51.8% no-vig market number, a 23.6% model edge at -112. Arizona Diamondbacks owns the starting pitcher edge by 8 points. Bullpen read: Adds caution. Arizona Diamondbacks's pen efficiency: Average (5.1/10). Bullpen fatigue moved this probability down 1.4 points from 76.8% (starting pitcher and team strength only) to 75.4%. Lineup check: Arizona Diamondbacks is a touch above its season form (+0.042 OPS); Athletics is a touch below its season form (-0.045 OPS). Recent form supports this side as well.
Final result
The pregame analysis remains on this URL. Postgame information is added without rewriting the original decision.
Game information
| Matchup | Athletics at Arizona Diamondbacks |
|---|---|
| Date | Tuesday, July 21, 2026 |
| First pitch | 9:40 PM ET |
| Venue | Chase Field |
| Starting pitchers | Jack Perkins vs Kohl Drake |
| Weather | Game-time forecast: 99°F, 4% precipitation chance, 4 mph wind from SW. This venue has a roof, but the roof status is not confirmed. |
Starting pitcher matchup
Full Pitcher Matchup Tool →| Metric | Athletics | Diamondbacks |
|---|---|---|
| Probable pitcher | Jack Perkins | Kohl Drake |
| Throws | R | L |
| LyDia pitcher score (higher is better) | 42 | 50 |
| ERA (lower is better) | 6.87 | Not available |
| WHIP (lower is better) | 1.44 | Not available |
| K/9 (higher is better) | 11.2 | Not available |
| BB/9 (lower is better) | 3.6 | Not available |
| K-BB% (higher is better) | 18.6% | Not available |
| HR/9 (lower is better) | 1.6 | Not available |
| Ground-ball rate | 39.2% | Not available |
| IP per start (higher is better) | 4.4 | Not available |
Pitcher edge: Arizona Diamondbacks by 8 points.
How to read this: highlighted cells mark a gap big enough to matter, not just any difference. K-BB% is strikeouts minus walks per batter faced, one of the most predictive skill stats in pitching. HR/9 is home runs allowed per nine innings. Ground-ball rate is neither good nor bad on its own: high ground-ball pitchers trade strikeouts for double plays and fewer home runs.
Strikeout projections Full K board →
Projections are self-calibrated against graded results (39 graded starts). Leans are context, not official picks.
Same data source as the Pitcher Matchup Tool, where every starter on the slate is compared side by side.
Offense and recent form
Full Stats page →| Metric | Athletics | Diamondbacks |
|---|---|---|
| Record | 43-57 | 51-49 |
| Last 10 | 2-8 | 6-4 |
| OPS, last 15 days | 0.685 | 0.737 |
| Season OPS | 0.730 | 0.695 |
| OPS change | -0.045 | +0.042 |
| Runs per game, last 15 days | 3.2 | 5.3 |
| K% season (lower is better) | 22.8% | 19.6% |
| K% last 15 days | 24.7% | 21.3% |
| OPS vs opposing hand | 0.742 | 0.667 |
Season and 15-day splits for all 30 teams live on the Stats page, including hot and cold streaks and the run environment table.
The Map
Full interactive map →Every team on today's slate, on any two axes you pick. Athletics and Diamondbacks are highlighted.
Bullpen matchup
Full Bullpen Fatigue Index →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.
| Metric | Athletics | Diamondbacks |
|---|---|---|
| Fatigue | 5.7/10, Normal | 7.9/10, Tired |
| Efficiency | 5.6/10, Effective | 5.1/10, Average |
| Combined risk | 5.4/10, Normal | 7.9/10, Tired |
| Relief innings, last 3 days | 11.3 | 15.3 |
| Back-to-back arms | 0 | 1 |
| 3-day ERA | 3.18 | 3.52 |
| 3-day WHIP | 1.32 | 1.50 |
Fatigue measures workload. Efficiency measures recent run prevention. Combined risk is what the moneyline and totals systems use.
Run total projection
Full Totals Projections →The model projects 1.0 runs above the market total. This projection is matchup context, not an official total pick unless LyDia explicitly labels it as one.
What could change the prediction
- A listed starting pitcher is scratched or replaced.
- The moneyline moves enough to remove the current model edge.
- A confirmed lineup materially changes the offensive matchup.
- Late bullpen availability differs from the recent workload data.
- Weather or roof conditions change before first pitch.
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