Modding games isn't easy. Generally you need a ton of people out there who actually know what they're doing before you get any halfway decent mods. And then, the game has to be set up to be easily modded. I promise you MLB is not one of those games.
Beyond that even, a modder can't go in and add errors and injuries to the game.
But you're right, because I only paid 30$ for the game I shouldn't expect it to get the same updates and patches as the console versions. I should just sit there and be happy because hey, I only paid 30$ for this awesome baseball game even though it doesn't have errors or injuries, and the pitchers stay in for 160 pitch 12 run complete games.
I'm so sorry to have offended you with my unrealistic expectations.