After the Nolan Arenado trade, the St. Louis Cardinals look primed to win the NL Central and maybe even make some noise in the playoffs. The season still needs to be played, but on paper, the Cardinals certainly got better by adding Arenado, and they certainly appear to be the best team in the NL Central.
However, if there is a weakness of the Cardinals this season, it seems to be the starting rotation. Bringing Wainwright back helped improve the unit, but there is still a lack of top-end potential in the group.
To begin with, Wainwright is a solid pitcher, but he is now 39 years old and is nothing more than a mid-to-back end of the rotation option. Additionally, Miles Mikolas and Kwang-Hyun Kim are solid pitchers, but neither project to be anything special. Of this group, Kim was the only one with a sub-4 FIP in the last two seasons, while all of them posted xFIPs above 4 in each of the last two seasons (Kim has only been with the Cardinals for one season). This does not give the rotation a high ceiling.
Jack Flaherty is still an exciting option even though he struggled last season. In fact, despite his struggles he actually posted a better xFIP in 2020 (3.42) , than he did in 2019 (3.64) when he was worth 4.8 WAR. This is an encouraging sign that Flaherty will bounce back this year. Additionally, Carlos Martinez currently projects to fill the fifth spot in the rotation. He is somebody who, like Flaherty, has plenty of upside. However, there is still plenty of risk with Martinez as he struggled last season and has to prove that his arm can handle a starter’s workload.
Among this group, Flaherty and Martinez are the only pitchers with real upside, but Martinez comes with plenty of risk even though he has pitched well in winter ball. Finally, beyond these five is Alex Reyes who has a checkered injury history and may not be able to hold up as a starter, even though he has the arm talent for the role.
After Reyes, the next best option would have been Austin Gomber, but he was just traded to the Rockies. This leaves Jake Woodford and Johan Oviedo as clear options while John Gant and Daniel Ponce de Leon may also be able to make spot starts.
However, neither Woodford nor Oviedo impressed last season when they were forced into spot starts. Of the two, Woodford is probably more MLB-ready as Oviedo could use some time in Triple-A, but Woodford is not an exciting option after allowing seven home runs in 21 innings in 2020.
Additionally, John Gant has not started a game since 2018, and I have already written about how Ponce de Leon profiles better as a reliever.
This leaves the Cardinals starting pitching options looking mediocre. Even without Gomber, the team will likely have enough depth to get through the season. However, with just Flaherty and Martinez having any real upside, this is a group that could be mediocre in 2021. Also, if any major injuries happen, the Cardinals will need somebody to step up. However, there is currently not anybody on the roster who appears to have the ability to give the Cardinals a couple months worth of strong innings as a replacement.
If the Cardinals are not confident with their depth options, then they could sign somebody in free agency. The Arenado trade opened up an extra spot on the 40-man roster which could be used to supplement the starting rotation. However, with the Cardinals looking to decrease their payroll from last season, it seems unlikely that they will bring anybody in.
The Cardinals also have a history of strong starting pitching depth, as well as a history of pulling pitchers from the minors and watching them have immediate success. This should work in the Cardinals favor, and create opportunity for a pitcher to impress, as teams rarely get through a full season with the same starting rotation.
This means that a young pitcher may get the chance to have a breakout season. With this in mind, a few pitchers that could break out are Oviedo and Angel Rondon. Oviedo is a promising prospect who looked over-matched in 2020, but has had an entire off-season to improve. Additionally, after a few months in Triple-A, Oviedo may be seasoned enough to rejoin the big league team.
Angel Rondon is a 23-year-old right-hander who dominated the hitter friendly Texas League (Double-A) in 2019 to the tune of a 3.21 ERA and 3.97 FIP. After not playing competitive baseball in 2020, we do not know how much he has improved. However, by the time Spring Training comes around, he will have had almost a year and a half to work on his game. This makes him a potential breakout candidate who could be a valuable pitcher for the Cardinals if he is forced into action because of an injury to starter.