Rockies vs. Diamondbacks — Sept. 24, 2026
The final home series of 2026 opens at Coors Field on Thursday afternoon, and the two clubs walking in could not be in more different places. Arizona is 84-74, still clinging to the periphery of the National League playoff picture with four games left on the schedule and needing an improbable cascade of help. Colorado is 57-101, playing out the string, already eliminated in all but the technical sense.
The betting market has noticed. So has Earl's model — but not in the places you might expect.
Tanner Gordon's Fatal Flaw at the Worst Possible Park
There is a version of Tanner Gordon's profile that looks like a usable big-league starter. He has walked 20 batters in 100.1 innings — a 1.79 BB/9 rate that would rank among the best in the sport. He misses enough bats, posting a 7.53 K/9 and a 4.2 strikeout-to-walk ratio. Command is not the problem.
Contact is. Gordon has surrendered 136 hits in those 100.1 innings, a 12.2 H/9 clip, including 19 home runs. That is a disaster profile at sea level. At 5,200 feet, in a park with an overall park factor of 113 and a home run factor of 117, it is an invitation.
His recent starts confirm the pattern rather than complicate it. Over his last five outings the Rockies have surrendered 9, 11, 10, 2 and 1 runs. Two of those games were winnable; three were not. His season line — 1-5, 6.01 ERA, 1.55 WHIP — is what happens when a strike-thrower with hittable stuff pitches half his innings in the most offense-friendly environment in baseball.
The Rockies have also been decimated on the pitching side. Chase Dollander, Sean Sullivan, Jeff Criswell, McCade Brown, Pierson Ohl and Welinton Herrera are all on the injured list, which means Colorado's bullpen depth is being tested every night behind a starter who rarely gives them length. That matters for totals and for late-game run-line swings.
Arizona Hands the Ball to Its Most Reliable Arm
| Pitcher | Record | ERA | WHIP | IP | K/9 | BB/9 | H/9 |
|---|---|---|---|---|---|---|---|
| Eduardo Rodriguez (L) | 15-7 | 2.89 | 1.23 | 183.2 | 6.86 | 3.04 | 8.04 |
| Tanner Gordon (R) | 1-5 | 6.01 | 1.55 | 100.1 | 7.53 | 1.79 | 12.2 |
Rodriguez is not a swing-and-miss ace — 6.86 K/9 and 3.04 BB/9 describe a pitcher who lives in the zone and trusts his defense. But he has been the most dependable arm on this staff all year, and his 2.89 ERA more than halves Gordon's.
The one caution flag is run support. In Rodriguez's last five starts, Arizona has scored 2, 6, 3, 1 and 2 runs — 14 total, an average of 2.8 per game. He won two of those (the 3-2 win over Houston and a 2-0 shutout of the Cubs) and lost three. That is the quiet reason the model stops short of projecting a blowout.
What Earl's Model Sees
This is where the analysis gets interesting, because the model's three picks are not all pointing the same direction in terms of conviction.
Earl's model projects a 5.1-4.1 Arizona win — a total of 9.25 runs and a home margin of -0.98.
- Moneyline: Arizona — correct side, but the model grades the expected value at -11.65, meaning the price has already been squeezed past the point of value.
- Over/Under: Under 10.5 — the model's total lands a full 1.25 runs below the posted number, yet the EV grade here is -4.04. The number is simply too high to attack aggressively.
- Run line: Colorado +1.5 — this is the model's real edge, carrying an EV grade of +13.63, by far the strongest signal on the board.
Read that carefully. The model believes Arizona wins — but by roughly one run, which makes the +1.5 on the Rockies the only bet on this game where the price and the projection are meaningfully out of alignment. A one-run Arizona victory covers both the moneyline and the run line, and the model's -0.98 margin sits almost exactly on that pivot.
The Line Is Moving, and It's Moving Toward Arizona
| Market | Opening | Current |
|---|---|---|
| Run line | 1.5 | 1.5 |
| Total | 10.5 | 10.5 |
| Colorado ML | +148 | +162 |
| Arizona ML | -176 | -194 |
The run line and total have not budged, but the moneyline has moved decisively. Colorado drifted from +148 to +162 while Arizona shortened from -176 to -194. That is roughly six cents of juice added to the favorite and fourteen points added to the dog's payout — a clear signal that money is landing on Arizona.
This creates an exploitable split. Public money is pushing the Diamondbacks toward a number the model already considers overpriced, while the Rockies +1.5 sits at a static price with a projected margin that lands right on the number.
The Offensive Numbers Will Surprise You
The casual read is that Arizona is the better team in every phase. It isn't — not offensively.
- Colorado: 4.63 runs scored per game — despite 101 losses
- Arizona: 4.46 runs scored per game
The Rockies out-score the Diamondbacks per game. What separates these clubs is run prevention: Colorado allows 5.80 runs per game, Arizona allows 4.42. That is the entire gap, reflected in run differentials of -184 versus +6.
So the correct framing isn't "Arizona's offense versus Colorado's pitching." It's "a competent Arizona offense versus the worst run-prevention unit in the sport, in the most hitter-friendly park in baseball." That points to Arizona scoring — but the Rockies have shown they can put up runs too, and 4.63 per game at Coors against a contact-oriented lefty is not nothing.
That dual-scoring potential is exactly why the model lands on a 9.25 total rather than something in the 11s, and why the Under 10.5 is noted but not recommended at this price.
Injuries Worth Tracking
Colorado's list is longer and more damaging: Willi Castro, Kris Bryant, Tyler Freeman, Chase Dollander, Sean Sullivan, Jeff Criswell, McCade Brown, Pierson Ohl and Welinton Herrera are all unavailable. Losing Bryant and Freeman removes two veteran bats from an already thin lineup.
Arizona is healthier where it counts. Tyler Locklear, Ryan Thompson, A.J. Puk, Andrew Saalfrank and Cristian Mena are out — mostly bullpen arms — but the starting rotation and core lineup are intact. In a late-September game where bullpen innings matter, that depth advantage is real, and it cuts toward Arizona holding a lead late.
How to Play It
- Primary play: Colorado Rockies +1.5 (+13.63 EV). The model's strongest signal by a wide margin. The projected margin of -0.98 sits almost exactly on the run-line number, and the price has not moved despite the moneyline shifting toward Arizona.
- Arizona moneyline (-194): pass. The model likes the side but grades the price at -11.65 EV. Backing a favorite at -194 to win by exactly the margin the model projects is the definition of paying for nothing.
- Under 10.5: pass, but note it. The 9.25 projection is 1.25 runs below the posted total, yet the EV grade of -4.04 says the market has already baked in the Coors discount.
- Public lean: Arizona ML. The public is right about who wins and wrong about whether it's worth the price. The sharp side of this game isn't the winner — it's the margin.
The headline story Thursday will be Arizona chasing a long-shot October. The profitable story is the one-run spread, and the number that hasn't moved.