What If: the Cardinals traded away a budding ace for a superstar third baseman?
Before Nolan Arenado, there was Jedd Gyorko, Jhonny Peralta, Matt Carpenter, and Tommy Edman, a motley crew of sorts. St. Louis struggled to find a true third baseman in the late 2010's. In order to fix that need, St. Louis traded for Nolan Arenado in 2021
In an alternate universe, that trade may not have been possible because the Cardinals had already filled their third base vacancy with a former MVP. Reports indicate that the Cardinals and Toronto Blue Jays were in talks to swap Jack Flaherty and Josh Donaldson back in the 2017-2018 offseason.
At the time, Flaherty was the team's #2 prospect and was ranked #38 in all of baseball. Alex Reyes, Dakota Hudson, and Jordan Hicks were all ascendant prospects, and the rotation was actually quite strong at the time. The team didn't need another high-end pitcher, but they did need a third baseman. Donaldson, an MVP as recently as 2015, would have filled that hole quite well.
While recent seasons prior to the 2018 season weren't as kind to Josh Donaldson, he was still one of the best third basemen in the league; he had a .277/.368/.511 slash line for his career after the 2017 season to go along with 174 home runs in just 831 games. Donaldson's bat was his calling card, but he was no slouch defensively at the hot corner.
If St. Louis would have traded Jack Flaherty before the 2018 season, they would have seen a fading Josh Donaldson at the plate for just one year due to his expiring contract. Donaldson played in only thirty-six games in the 2018 season due to various shoulder and calf injuries. In exchange, the Blue Jays would have gotten a very young, very talented, very controllable starting pitcher.
Jack Flaherty, through all of his injuries and frustrations, was a good starting pitcher during his tenure in St. Louis, particularly in 2019. If the Cardinals had traded him off before the 2018 season, we may not have been able to see Flaherty's masterful second half in 2019. I do suspect the Cardinals trade for Nolan Arenado down the road in this universe, as I don't expect they would have extended Donaldson after a miserable 2018 season. St. Louis could have even signed a veteran Mike Moustakas to fill Donaldson's absence the following offseason.