Last week, I suggested Chase Dollander could be a bounce-back candidate in 2026, despite only completing his rookie year in 2025. However, he could also just be a candidate for continued development.
But then a comment caught my eye from Colorado Springs Northsider:
A number of Rockies pitchers have taken a season or two (Cook and Gray in particular) to acclimate to Coors Field and I would hope he’ll be like them and actually pitch better at Coors than on the road.
In September, Skyler Timmins wrote
about what Dollander might learn from Rockies legend Ubaldo Jiménez. But this week, I’d like to take a look back at the careers of Aaron Cook and Jon Gray to see what we might expect from Dollander if he follows a similar path.
Aaron Cook
Aaron Cook was drafted by the Colorado Rockies in the second round of the 1997 MLB Draft, 70th overall, out of Hamilton High School in Ohio. He made his MLB debut on August 10, 2002, against the Chicago Cubs, pitching two innings and allowing one run — a solo homer. Cook pitched four games out of the ‘pen, but then made his first MLB start on August 26 at home against the San Francisco Giants. In that outing, he threw six innings and allowed three runs (two on a home run in the first inning) with four walks and zero strikeouts.
Cook fought injuries and inconsistency through his first three years, most notably undergoing thoracic outlet surgery in September 2004 after suffering from blood clots in his right shoulder and in addition to a non-displaced leg fracture in September 2010. However, he was the Rockies Opening Day starter in 2007, but missed time with a side injury late in the season, including the first two playoff series. Cook did start Game 4 of the World Series, though, and was named an All-Star in 2008. He also threw two complete-game shutouts on fewer than 80 pitches.
So the peak of his career happened in Years 5 and 6 for him, and he is now highly regarded in Rockies lore.
Cook pitched for the Rockies until 2011, when he signed with the Boston Red Sox in January 2012. He pitched there in 2012 before returning to the Rockies just ahead of spring training in 2013, where he retired at the end of that season after pitching for the Triple-A Colorado Springs Sky Sox. (He did sign a minor league deal with the Philadelphia Phillies in January 2013 with an invite to spring training, but was cut at the end of March, setting up his Rockies return.)
In his career, Cook boasts a 4.65 ERA at Coors Field, and a 4.48 ERA on the road. Cook also ranks among Rockies leaders in career bWAR (17.1, 3rd), ERA (4.53, 5th), wins (72, 2nd), innings pitched (1312.1, 1st), strikeouts (558, 10th), starts (206, 2nd), ERA+ (106, 7th), and FIP (4.39, 7th).
Much of his success came with the command of his sinker, which is crucial in a hitter-friendly park like Coors.
Jon Gray
“The Gray Wolf” was drafted third overall in the 2013 draft out of Oklahoma University and made his debut two years later on August 4, 2015 against the Seattle Mariners at Coors Field. He started the game, pitching four innings and allowing three runs (two earned) on five hits with two walks and four strikeouts.
Gray had some big highlights, including his 16-strikeout complete-game shutout against the San Diego Padres and starting the 2017 Wild Card game.
He was also named the Opening Day starter for the 2017 and 2018 seasons, but was not named to the 2018 NLDS roster.
Gray, like Cook, also struggled with injuries during his career in Colorado. In 2019, he dealt with a stress fracture in his left foot and made only eight starts in the COVID-shortened 2020 season due to right shoulder inflammation. He was a potential trade chip in 2021, but the Rockies held on to him in hopes of coming to a deal. They also did not make him a qualifying offer, and he ended up signing with the Texas Rangers.
Since he joined the Rangers, Gray has continued to be plagued by injuries and was converted to a reliever in 2023. That worked out well for him, as he tossed three scoreless relief innings in Game 3 of the 2023 World Series en route to the Rangers eventual victory over the Diamondbacks. He then spent much of 2024 on the IL, and then fractured his wrist in spring training 2025. Finally, Gray was placed on the 15-day IL with thoracic outlet syndrome in August and hasn’t pitched since. He is currently a free agent.
Like Cook, it took Gray a little seasoning before he became “The Gray Wolf.” The 16-strikeout game was definitely his coming out party. Unlike Cook, though, Gray relied heavier on his fastball and slider, which had a tendency to get hit out.
He ranks among Rockies leaders in bWAR (11.5, 8th), ERA (4.59, 7th), wins (53, T-8th), WHIP (1.338, 3rd), K/9 (9.213, 1st), innings pitched (829.1, 8th), strikeouts (849, 4th), starts (151, 7th), ERA+ (107, T-5th), and FIP (3.91, 2nd).
Chase Dollander
Dollander was drafted ninth overall in the 2023 draft and made his MLB debut on April 6, 2025. He had an up-and-down season and was plagued especially by home runs (something Jon Gray also struggled with much of the time). He made a total of 21 starts in 2025, posting a 6.52 ERA. However, his home-road splits were massive. At Coors Field, Dollander posted a 9.98 ERA in 46 innings; away from Coors Field, Dollander posted a 3.46 ERA in 52 innings.
Looking at these two Rockies pitchers, Dollander could learn one thing from each of them:
- From Cook, control of the breaking ball
- From Gray, narrowing the home-road splits
Cook relied heavily on his breaking pitches, and it worked well for him, especially in his mid-career. His best seasons came in 2007 and 2008. Gray had consistency both at home and away. During his time with the Rockies, he posted a 4.54 ERA at home and a 4.65 on the road. That’s something that Gray worked on, as well. In his first year with the Rockies, Gray posted an 8.27 ERA in five games at Coors Field and a 2.70 ERA on the road in four games. It’s to be expected, especially with a young pitcher trying to figure out the environment, but the following year, he posted a 4.30 ERA at home in 14 games and a 4.91 ERA on the road in 15 games.
If Dollander can heed the lessons of those paved before him, he might be a candidate to bounce back in 2026 and perhaps start to dominate like we expect him to in 2027 or 2028.
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MLB Network started their “Top 100 Players Right Now” countdown on Tuesday, and Hunter Goodman — fresh off a career year that saw him named to the All-Star Game and win a Silver Slugger after hitting 31 home runs — slid in at No. 97.
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