Really anymore most teams don't want the "Bell Cow" back to get a ton of carries in the preseason. My guess is Ball would have gotten maybe 10-15 carries in the preseason anyway. The team is more interested in finding out what they have in especially the undrafted guys that are fighting for that 4th and final RB spot on the team.
And yeah it really is a pretty minor procedure. My doctor told me I could play 18 holes on the golf course the day after surgery if I wanted to. I was back in the weight room probably a week and a half after surgery and that was just because I was being cautious. He should be ready week 1 no problem.