It appears injuries can be added, but any team you add them to, random guys in the minors will have their names changed. It's a combo of Norichika for the first, last, and sometime first and last. What you have to do is use a franchise file, and then sim until right before the injuries. For my Cubs dynasty I made all injuries start on April 1st because I had trouble with the franchise freezing when I entered them when they actually went on the DL. Then I went back into my franchise and looked at the minor league guys who's name changed to Norichika and corrected them. You must use the ReEditor to correct names otherwise even more will be screwed up. So far there has been no freezing in my franchise and all the guys who I entered as on the DL are. The only problem is the game will freeze when you look at League Injury history. Not sure why but as long as you don't look at the injuries everything is OK.
Took some time to figure this out but it does work if you put some time into it. I did not sim an entire season so I cannot be 100% that it won't freeze during the year, but about 1 week in everything is ok. Just don't look at Injury History.
Comment