Okay, I know it's not technically the weekend anymore. Nonetheless, here is my new League Setup mockie, as promised!
Before I begin, I should point out that I cropped off everything except for the central part of each screen I'm describing. This includes the list of leagues that appears to the left, the buttons along the bottom, and all the headers and footers. I'm not recommending they be removed from the screens in the game. I just left them out here, since they don't include any significant modifications.
Oh yeah, and be sure to pace yourself, because there's a LOT to process here.

(Just don't say I didn't warn ya!

)
Now, on with my ideas!
In my proposed redesign, there would be 6 types of leagues...
- Major League - In addition to MLB, this category would include the top levels of any international or independent league in one's universe.
- Minor League - I've made very few alterations that are unique to the Minors category. Most changes mirror those of the Majors category.
- Instructional League - These would include offseason developmental leagues, like the Arizona Fall League. What makes them unique in this structure is that players would be able to concurrently appear on their affiliated major/minor league roster. Otherwise, most options here are similar to the Minors category.
- College League - No longer labeled a "Feeder League", the Colleges category would still feed other leagues, but have more options that allow them to operate as a standalone league. Colleges would be subdivided into 4-Year and 2-Year levels, with players from 2Y schools feeding into and transfering to/from 4Y schools and both levels feeding amateur draft(s) at the Majors level.
- High School League - Like the Colleges category, High School leagues could function on their own. Players would feed into both 4-Year and 2-Year schools, as well as directly into the amateur draft of affiliated major league(s).
- Tournament League - Unlike the other types of leagues, this playoff-only format doesn't involve a regular season or even a permanent structure. (Although, similar to Instructional Leagues, their teams would be temporarily populated with players that concurrently appear on rosters in other leagues.) There would be 4 subdivisions of Tournament Leagues: Champions League (between champions of multiple leagues), International Competition (between players from different countries), Inter-Regional Competition (between players from different states or regions), and College/HS Tournament (between schools from different conferences, as in the College World Series).
For each League Type, there would be 7 different League Setup screens, which could be accessed via the tabs at the top of each screen. The examples below would be the default settings for a "Major League", specifically Major League Baseball. I'll go through each screen individually and describe the changes and additions I made.
Note that while the "Strategy" screen remains, I didn't make any alterations to it, so I didn't cover it below. Also take note that the "Functions" tab has been eliminated, as the "Function" button at the bottom of the screen basically serves the same purpose. (Plus, a League Wizard button could easily be added to the same area at the bottom, since it doesn't seem to really "belong" where it currently is.) Finally, I want to point out that I mis-labeled the Schedule screen/tab as "Season". Even though I neglected to change it, I do think "Schedule" is a better title.
Here are descriptions of all content that has been added to, altered, repositioned within, moved to, moved from, and removed from each screen...