Mariners vs Rockies Prediction, September 18, 2026 | Mariners moneyline
Bryan Woo vs Unlisted at Coors Field
Published September 18, 2026 · MLB Prediction Data Lab
The moneyline on Mariners at -181 is a run-prevention bet first. Bryan Woo projects 4.00 earned runs allowed across a 5.80-inning start plus relief; Unlisted projects 4.75. The side that prevents more does not have to outslug anyone.
Full slate: MLB picks today, September 18, 2026.
The listed matchup
Seattle Mariners (71–82) at Colorado Rockies (56–97), Coors Field, Denver. Bryan Woo, a right-hander, is listed for the visitors. Unlisted, a starter, is listed for the home club. Void the play if either listed starter is scratched.
| Side | Listed starter | Record | Park |
|---|---|---|---|
| Mariners | Bryan Woo | 71–82 | Coors Field |
| Rockies | Unlisted | 56–97 | Open, grass |
The two starters, measured per batter faced
Rate statistics expressed per nine innings reward pitchers who work deep. Expressing them as a share of batters faced removes that distortion. Bryan Woo has faced 657 hitters. Unlisted has faced —.
| Starter | BF | K% | BB% | K−BB | K/BB | Pitches/BF |
|---|---|---|---|---|---|---|
| Bryan Woo | 657 | 24.8 | 5.3 | 19.5 | 4.66 | 3.77 |
| Unlisted | — | — | — | — | — | — |
| Starter | W-L | ERA | IP | WHIP | K/9 | BB/9 | HR/9 | Opp AVG |
|---|---|---|---|---|---|---|---|---|
| Bryan Woo (R) | 12-9 | 3.88 | 162.1 | 1.05 | 9.04 | 1.94 | 1.00 | .221 |
| Unlisted () | —-— | — | — | — | — | — | — | — |
Bryan Woo sits at a 3.88 ERA with a 1.05 WHIP and 35 walks in 162.1 innings. Unlisted sits at a — ERA with a — WHIP and — walks in — innings. Walks stabilize faster than earned runs, so the walk column is the more trustworthy August reading.
Direction inside the season
Season aggregates hide the last month. These are the prior starts, excluding today's outing so the table does not leak a result into a published prediction.
| Bryan Woo — last starts | IP | ER | K | BB | H | HR | Pitches |
|---|---|---|---|---|---|---|---|
| 2026-08-16 | 6.0 | 2 | 5 | 1 | 3 | 2 | 75 |
| 2026-08-26 | 4.0 | 6 | 5 | 1 | 5 | 2 | 76 |
| 2026-09-01 | 6.0 | 1 | 7 | 1 | 5 | 1 | 99 |
| 2026-09-06 | 8.0 | 0 | 9 | 2 | 1 | — | 102 |
| 2026-09-12 | 6.0 | 0 | 5 | 2 | 3 | — | 80 |
No prior 2026 game log is posted yet for Unlisted.
The run environment, before the starters
Mariners have scored 624 runs in 153 games (4.08 per game) with a .692 OPS. Rockies have scored 717 in 153 (4.69) with a .741 OPS. The pitching staffs have allowed 4.44 and 5.84 runs per game.
| Club | Record | R/G | OPS | Staff ERA | Staff WHIP | RA/G |
|---|---|---|---|---|---|---|
| Mariners | 71–82 | 4.08 | .692 | 4.21 | 1.26 | 4.44 |
| Rockies | 56–97 | 4.69 | .741 | 5.62 | 1.54 | 5.84 |
Reassembling the buckets
Bryan Woo averages 5.80 innings per start. Unlisted averages 5.50. Weight each starter's own earned run average across that length, then hand the remainder of the nine innings to his club's season staff rate. That is a conservative relief proxy — it mixes rotation and bullpen — and it is stated as a limitation, not hidden.
| Side | Starter IP | Starter ERA | Relief IP | Staff ERA | Projected ER |
|---|---|---|---|---|---|
| Mariners (Bryan Woo) | 5.80 | 3.88 | 3.20 | 4.21 | 4.00 |
| Rockies (Unlisted) | 5.50 | 4.20 | 3.50 | 5.62 | 4.75 |
| Combined | 8.75 |
A combined 8.75 projected earned runs. Unearned runs are ignored. Neither starter hits his average length every night. The opposing lineups are not in the formula; they sit in the table above.
The park
Coors Field is listed at 347 feet to left, 420 feet to left center, 415 feet to center, 424 feet to right center, 350 feet to right, on grass, open at 5190 feet above sea level with a listed capacity of 50,480. Park dimensions do not decide a total by themselves. They decide whether a walk plus a ball in the air becomes two runs or a long out.
Where this reading is weakest
Moneyline edges this thin die when the length assumption fails. If the better starter is out in the fourth, the staff rate takes over and the partition no longer applies.
What would falsify it
A short outing from the starter on the backed side, or a crooked inning against the relief bucket that the partition treats as average, is the miss. The model is only as good as the length assumption of 5.80 and 5.50 innings.
The position
Seattle Mariners ML at -181, 2 units. A price of -181 implies a 64.4% break-even. Grade it against this published number. If a listed starter is scratched, the play is void.
- Seattle Mariners ML -181 · 2u
Who is on the mound?
Bryan Woo for Mariners. Unlisted for Rockies. Those names come from the MLB probable-pitcher feed, not from a guessed rotation.
Why use batters-faced rates instead of ERA?
Earned run average is a counting result. Strikeout and walk rates as a share of batters faced describe the process that produced it, and they stabilize on a smaller sample. Bryan Woo at 19.5 points of K−BB separation versus Unlisted at — is the comparison ERA hides.
How is the pick graded?
Against the published price, on the public record. Pending is not a win. Today's full card lives at a stable URL: mlb-picks.html.
Pick, odds, and unit size come from the BetLegend daily tracker. Probable starters, season rates, and venue facts are from the MLB Stats API. Educational analysis. 18+ only. 1-800-GAMBLER.