Let's break them down:
The September Callup Rule:
Every Teams roster expands from 25 to 40 in the month of September. These spots are usually filled with prospects from the Minor Leagues.
The Argument: Some teams Minor League teams are in the playoffs in September. The Major League club normally doesn't want to interfere with the teams. So, they don't callup anyone.
This could give some teams an advantage because if they have 40 men on their roster and the team they are playing only has 32, the team with the 40 players has more depth in ethier the bullpen, or on their bench. So, if the game goes to 14 innings, the team that has the more players could have an unfair advantage because they ethier have more depth in the bullpen or on their bench that they can use in the late innings.
The Solution: Every Major League club would have to have 30 players on its roster in September. No more, no less. Thus, this eleminates the problem above.
The Intant-Replay issue has been a problem for a long time. It may just be time to put that to rest. Instant-Replay is only used in specific cases; like in the event of fan interference or homer or no homer. This causes the umpires to blow plenty of calls. Whether they are important or not, that is really what matters.
The Arguement: Remember Armando Gallaraga's Perfect Game? Oh, right Jim Joyce blew the call that would've done it. The batter was out at first base, but Joyce called him safe. From that day forward if any umpire blew a call, I would say, "He Jim Joyced it!"
The Solution: Expand Replay. Please, MLB! It helps the game improve when you can check to see if you're right! It would really help knowing that the right call was actually made on the field!