Graf didn't have more serious injuries than Serena. Well let me rephrase that, she didn't have as many inopportune injuries as Serena did. Serena got her career threatening injuries when she was the dominant player and No.1 in the world. 2003, she had won 5 of the last 6 slams, then after the knee surgery took her almost 2 years to win another with a year long lay off, and movement was grossly affected. 2010, won 5 of the last 8 slams, a foot injury having nothing to do with tennis, surgery, and then she's out for another year, making it another 2 years before winning a slam. Not comparable. Could you imagine Graf having a knee operation in 1989, or 1993? It would've taken her months to recover. Graf did eventually have knee surgery, but it was at the end of her career. Not to say it didn't affect her and her game, because it did, but it's one thing to have these unfortunate health problems at the end of your career than it is when you're the dominant No.1 with no plans of stopping in the foreseeable future.
Just for a change, you're getting basic facts wrong. Graf's 1994 season was completely ruined by a back injury, after she had completely dominated 1993 (and by the way, this is another reason why the "Graf's career was made by Seles's stabbing" school of thought is silly - because Graf was too injured to take advantage for half of Seles's hiatus). And then, after her second period of utter dominance between 1995-96, she was wiped out completely by injury.
And, nobody in the history of women's tennis can touch Serena if she serves on grass like she's done this year. Although, she had tight matches with Zheng and Shvedova at Wimbledon, she took care of her serve. And once she broke, the set was over.
Shvedova and Radwanska broke Serena's serve multiple times.....and Graf wouldn't be able to
Once again, Steffi handled Serena and Venus serving almost as well as Serena does now back in 1999, and she handled it just fine. And Steffi had a pretty considerable serve of her own, you know (again, this is another thing where people on here talk like the from the late 20th century all had Evert-type puffball serves, when in reality, Graf and Navratilova would regularly crack serves at over 100mph).
There's no way Serena is going to play more than about 10-12 tournaments a year so if you're looking her to break records, it's not going to happen. Graf regularly played 15+ tournaments a year week in and week out.
And similary, that's why Serena being considered better than Graf (by non-Americans) is similarly not going to happen. And by the way, Graf would usually only play 11-14 tournaments a year, which really isn't that much more than Serena atall - the reason she played so many more matches is just because she was better and would go deep in nearly every tournament she played - unlike Serena.