Last season, the Cardinals had plenty of infield depth as Tommy Edman and Brad Miller were able to start at third base or provide flexibility at other positions while Paul Goldschmidt, Kolten Wong, and Paul DeJong started at the other three infield positions. However, the Cardinals appear to be willing to move on without Wong and Miller. Presumably, this pushes Edman into a starting role at second base, while leaving nobody but Matt Carpenter at third base. This is clearly a problem that will need to be addressed before the season begins, especially considering how Matt Carpenter has played lately. Additionally, it does not appear likely that the Cardinals are going to be able to find an in-house solution. This means that the organization must look outside for an acquisition that is capable of playing third base and, hopefully, could also provide a decent bat to the lineup.
To begin with, Matt Carpenter posted a 95 wRC+ in 2019 and a 84 wRC+ in 2020. This is not good enough for a Cardinals lineup that can struggle to score runs. However, the Cardinals have a notable lack of in-house options at the position as the top candidates are likely Elehuris Montero, Edmundo Sosa, Evan Mendoza and Juan Yepez. None of these options are particularly exciting as Montero struggled in Double-A in 2019, Sosa has never been a great hitter, Mendoza also struggled in Double-A in 2019, and Yepez has just 59 plate appearances above A-Advanced and also struggles defensively. Sosa is probably ready for a full time backup role in St. Louis, but he is likely not going to hit enough to be a starter. Additionally, Montero and Mendoza spent time at the Cardinals alternate training site in 2020, but they needed to show serious improvement if either of them are going to be handed a starting role after their struggles in 2019.
Another option is to play Edman at third base, but that creates a hole at second base. Additionally, since the Cardinals need to add a bat to the lineup, it is likely better for them to look for a third baseman. Therefore, since in appears that none of the internal options can be capable starters for the Cardinals, the organization must look for an external acquisition.
There are multiple ways that the Cardinals could do this. They could see who gets non-tendered and try to make a move for someone that could play third. This would likely be a relatively cheap option. The Cardinals could also sign a free agent. In this case, the team would likely look at a veteran that can be acquired on a short term contract because it seems unlikely that the team would be willing to block Nolan Gorman. There are plenty of candidates on the market who could play either second or third, although none of them are particularly exciting. If the Cardinals do not want to make a move here, then they should shop in the trade market. This could be an effective strategy because most teams will likely be willing to hear offers that will take payroll off their books. The Cardinals are likely not going to want to add much payroll, but they might be able to work something out and acquire a veteran bat or a younger player with more positional versatility.
Regardless of what the Cardinals do, one thing is clear - Matt Carpenter should not be a starter. If the Cardinals have playoff ambitions in 2021, then they will need to add somebody who can play third and who can hit the ball better than the league average hitter. If the Cardinals want to rely on internal options, then they are likely to be disappointed as it does not appear that anyone is good enough to step up and establish himself as a solid MLB third baseman.
In all likelihood, the Cardinals are going to look for another Brad Miller - a veteran that signs a cheap, one year deal and then over-performs. While it is possible that this happens again, if the team does not sign the right player, then it will be struggling for production from third base. Therefore, it might be more prudent to spend a bit more money to secure better production, instead of hoping for another Brad Miller.