If you want to improve the perceived floor/risk of the starters, let's go get Brandon Woodruff from the Brewers (we can discuss that more) but you are likely trading out Kremer to do something like that. That doesn't change your depth, it might change your floor...but their ERAs were the same in 2022...so I'm not sure it moves the upside much at all.
Woodruff
Manaea (Means)
GRod
Voth (Hall)
Bradish
Sure, its possible to find some cheaper or in-house option that might pitch as well as an expensive addition. The one sigma thing that you talk about will have some overlap for a $25M arm and a $10M arm and even areas where the cheaper guy is ahead. But that's not the most probable outcome. I'm hoping to build as good of a team as possible next year. Push the center of those bell curves as high up as I can. Punting on improving the SP would not achieve that goal.
I don't disagree with what you're talking about the curves, I just think there's more overlap than you are assigning.
It's the Woodruff versus Kremer thing in the post above what you wrote. I'm all for that move, but it's entirely possible it works out poorly. Woodruff is better in every respect, but he costs more to acquire, you need to commit money to get the time to match (or not worry about it).
Brewers have over a dozen arbitration cases. They are going to need to do some things to align their roster this offseason. Commitments to Yelich means they aren't likely to quit and start over (no point in that), so they need some trade partners to accomplish different things. Woodruff is ARB2 and MLBTR has him projected at 11M (let's use that). Woodruff has outperformed expectations in 2018 (we can probably find a thread discussing him for Schoop). Kremer had some solid expectations and then failed horribly, but bounced back in 2022 to pitch very well. The Teams are in different positions and can trade out performance risk for cost risk. The Brewers would get a lot more in that exchange, but it (or something like it) IS available and there's certainly ways to make it happen.
There's certainly things you can do to improve quality, but there is real opportunity without it, if we do the other things. I'm not against doing more. They aren't going to do more and they probably don't even do the minimum, but we'll sEve.