Number 55- Jon Gray
Unless you think that Danny Ardoin or Mark Redman are serious challengers for Jon Gray at number 55, no one else really holds a candle to Gray at number 55.
In part of five seasons as a member of the Rockies starting rotation, Gray has put himself in the discussion as one of the best Colorado Rockies starters in their franchise history.
He did have a bit of a hiccup in the 2018 season when he was sent down to Triple-A Albuquerque for a short period but in 2017 and 2019, he was one of, if not, the Rockies best starting pitchers.
Gray has an ERA of 4.46 in 115 games (114 starts) with an ERA+ of 110 and a FIP of 3.77. 2017 was his best season when he pitched to a 3.67 ERA (3.18 FIP) in 20 starts. His strikeout-to-walk ratio was best in this season and his average home run rate was lowest in 2017 as well.
Number 56- Greg Holland
Franklin Morales is the only one that really gives Greg Holland any competition here considering Morales spent six seasons with the Rockies and Holland was only a Rockie for a season but Morales was mediocre in his six seasons and Holland was very good in his only season.
In that season (2017), Holland was an All-Star and he led the National League in games finished (58) and saves (41). He had an ERA of 3.61 but that was largely due to his disastrous month of August. Entering August 6 (when he had 42 of his 61 appearances), he had an ERA of 1.56 and his ERA in his last 11 games was 1.69. In those middle eight games, though, his ERA was 19.69.
He allowed 14 earned runs in those eight appearances and just nine earned runs in the other 53 appearances.