It's part of being a wrestler to be overworked. They're always doing something wrestling related. For many guys, a day off is doing an autograph signing or something like that. When they aren't in the ring, they are still having to work out, travel, etc. Not to mention the countless matches they're in over a year's span. Many of those matches are stipulation matches like last man standing, ladder, tlc, cage, etc. - all matches that can result in an injury or even end a career if something doesn't go as planned. It's a huge wonder why more people don't end up with injuries than they do.
It's sad that so many top-tiered guys have been getting injured lately. For anyone that hasn't read it, there is a story up on WZ's front page about Punk walking away from ringside after his match tonight with a limp and with the assistance of two other guys (presumably two people from the medical staff). Now whether Punk was selling the spot from Raw tonight when Edge shoved him off the top rope resulting in his knes hitting the steps, or if he was legitimately hurt to some degree, isn't clear at this point. He could've really been injured in that spot, because it was pretty dangerous looking. He did end up winning the match, but people have finished matches with injuries before. If he his injured, then there is hope it is only something minor, because losing Punk to an injury at this point would be a real blow to the WWE.
Back to the point, wrestling is a dangerous industry to take part in. Injuries occur quite frequently, more so lately than what we're used to. Plus, when it's a main event status person like Batista, we notice it more. Add to that the fact that his injury happened on the heels of a title win and it places even more of a spotlight on the situation. Most of the guys who have been suffering injuries lately are guys that have been the work horses for their respective shows. Think about how often we see Batista, Punk, Hardy, and others in matches. More to the point, they are often the ones in the best matches on the card. Those real wrestling matches, full of back and forth action, great in ring psychology, and (with Hardy in particular) some pretty dangerous spots. It's one thing to take place in a squash match or to be in a so-so match, but it's an entirely different kind of thing to be part of a 10-15 minute, honest to goodness wrestling match. At most house shows, it's guys like Punk and Hardy that are in that sort of action each and every night. It is only natural for their bodies to get worn down from all that. To answer you question, I doubt that it's a result of carelessness on their part. It is much more logical to realize that these injuries are results of tired bodies being pushed to their limits.
