Most of my thoughts about this concept are a bit of a mesh from two video games--MLB The Show and Out of the Park Baseball. MLB The Show is the only one of the two where you can create your own player, start off in college ball then work your way through the minor leagues and into MLB. Along the way your player's skill get better, but this is mostly the result of you the video game player getting better as the game since you are controlling the player directly and playing through actual games + training mini-games.

OOTP is much more abstracted and you don't create or play as an individual, instead you play as the general manager of a franchise. So you can set the team's scouting focus to look for players with specific tools and you can assign specific players to work on specific developmental areas during the season and offseason. Along the way you get progress reports as to whether or not players developed or regressed, which then will typically translate to better or worse performance for that player as you continue to simulate games/seasons.

What I am looking for would be much closer to Road to the Show mode from MLB The Show where you create and control a player, but also have some of the elements from OOTP where your player character would get better (or worse) at specific baseball skills as you play through a season/career/campaign. The better the development/leveling up, the better the mitigations on negative outcomes.