Why it makes sense for St. Louis in the short-term:
I know this will never happen. There is just no way that the Cubs would trade Justin Steele to the Cardinals. I also do not see the Cardinals giving up this kind of talent to their division rival. But let's be honest, the framework makes a lot of sense.
The Cubs plan on selling at this year's deadline after another disappointing season. Chicago is not going to go into some full-scale rebuild, but there are rumors that they will consider maximizing Steele's value to help the club going forward. My oh my, Steele would be the perfect fit with Gray at the top of the Cardinals' rotation.
In 15 starts for the Cubs this year, Steele has a 3.07 ERA while covering 91 innings, and Steele continues to be elite at not allowing hard contact and getting hitters to expand their zones. Not only that, but lefties tend to excel when pitching at Busch Stadium, so we could even see the best of Steele yet to come in a Cardinal uniform.
Gray and Steele would give the Cardinals a formidable duo this October, and in this package, not require a single piece from their Major League roster to be moved. Hence is a top pitching prospect in all of baseball that would bolster an already loaded Cubs system, and Gordon Graceffo would provide them with further pitching depth that can cover innings now as well.
Ivan Herrera has his clear weaknesses defensively, but the Cubs have had terrible production from their catcher position ever since they let Willson Contreras walk in free agency. Developing Herrera behind the plate now could give the Cubs an everyday catcher to match up with Contreras in the coming years.
Why it makes sense for St. Louis long-term:
Steele is not a free agent until 2028 giving the Cardinals a cost-controlled arm for years to come. Steele is who we hope Tink Hence can become, and a bird in the hand is better than a bird in the bush. Herrera and Graceffo is not a crazy premium to pay along with the potential of Hence to get what we know Steele is.
What doesn't make sense for them long-term is giving the Cubs assets, but hey, if someone else is going to do it, does it really matter all that much? I'm sure the Cubs would prefer to squeeze St. Louis for more value though, or just deal Steele elsewhere.