While the Rockies current starting pitchers have been solid if not spectacular, there will inevitably come a point in the season in which the team will need additional depth in the starting rotation.
The Rockies current starting staff, consisting of Jhoulys Chacin, Jorge De La Rosa, Juan Nicasio, Jeff Francis and Jon Garland, currently ranks 15th in MLB with 2.2 fWAR and is 18th in the league with a 4.36 ERA, both numbers that are vastly improved from the train wreck that was the 2012 rotation, which was good for a measly 4.7 fWAR and 5.81 ERA.
However, unless the teams sees a string of good luck and performance like it saw from the starting rotation in 2009, when the same five starters were on the mound for 155 of 162 games, depth in pitching will become an issue at some point this season. Whether it be because the team feels someone like Jeff Francis or Juan Nicasio is not pitching well enough to remain in the rotation, or there are injuries that creep up, pitchers that are currently in the minor leagues will almost certainly be called on to start games at the big league level.
The most obvious replacement would be someone that has already been with the club this season, Tyler Chatwood. The 23-year-old righty made a pair of starts for the Rockies while Chacin was on the disabled list with a back issue. He performed quite well in those starts, allowing just four runs in 12 innings of work with three walks and eight strikeouts. At AAA Colorado Springs he has been dominant, posting a 1.14 ERA in four starts including a complete game shutout on Tuesday.
Chatwood is an interesting case, he was brought to the majors with the Angels in 2011 at age 21, earlier than they would have liked, because of a rash of pitching injuries at the big league level. He performed quite admirably for someone who was rushed to MLB as he was, posting a 4.75 ERA in 142 big league innings. The story was similar for Chatwood in 2012, as he was again brought to the big leagues thanks to injury issues, this time as a 22-year-old. He did not perform as well as in 2011, thanks mostly to a HR/FB rate that doubled from the previous season, posting a 5.43 ERA in 64 2/3 innings in a Rockies uniform. Both his minor and major league numbers have seen a dramatic improvement in 2013, albeit in a small sample size, but it looks like he may be ready to be a consistent performer at the highest level.
If the club is looking for a southpaw, there is always the option of Chatwood's Sky Sox teammate, Drew Pomeranz. The centerpiece of the Ubaldo Jimenez trade was a candidate to make the major league rotation out of spring training, but was beat out by Garland. He has responded well at AAA, posting a 4-0 record in six starts with a 3.51 ERA (3.32 FIP) and 10.8 Ks per nine innings with the Sky Sox.
Pomeranz made 22 starts for the Rockies last season as a 23-year-old, posting a 4.93 ERA and 0.9 fWAR in 22 starts and 96 2/3 innings in the big leagues. Pomeranz is already on the 40-man roster, so the only issue with calling him up should be whether the team feels he is ready for the role.
If the club is looking for a more veteran option, 35-year-old Roy Oswalt was signed to a minor league deal last week and is currently in extended spring training. The three-time all-star posted a 5.80 ERA in 59 innings with the Texas Rangers last season, but performed much better in a bullpen role than as a starter.
What Oswalt does bring to the table is 163 wins and a 3.28 ERA in his big league career, and he could fill a leadership role if the Rockies were to lose Francis and/or Garland. He also has stellar career numbers at Coors Field, where he is undefeated with a 2.25 ERA in five starts, The team would obviously have to clear a 40-man roster spot for him, and may view Oswalt more as a reliever at this point in his career.
If you're looking for a longshot to see the majors ans succeed there in 2013, the one to look at is Chad Bettis. Bettis, who missed all of 2012 with a shoulder injury, has put together a string of five very good starts in a row at AA Tulsa. The 24-year-old was the Rockies' second-round draft pick in 2010 and very well may have been first in line for a call up this season if not for the injury.
Bettis has been impressive at every level of the minor leagues so far in his career. In 267 2/3 innings in his pro career, he has posted a 2.86 ERA and his 3.01 FIP in Tulsa this season is his highest at any minor league stop. At the very least, expect to see Bettis as a September call-up in 2013.
I feel obligated to mention Aaron Cook here out of respect for what he's done for the franchise, but make no bones about it, if the Rockies career wins leader gets a chance to add to that total in 2013, something has gone very wrong. Cook is with the Sky Sox this year and has not pitched well, posting a 7.40 ERA in 24 1/3 innings. He hasn't posted an MLB ERA below five since 2009.
This is not to say that all of these players will or even should be in the Rockies starting rotation in 2013, simply that if and when a replacement for one of the current starters is needed there are several options that have a good chance to succeed in a replacement, or even a permanent role.