I'll tell you what happened, it's a simple formula
Little formal wrestling training + starting at a late age + getting older by the minute + injury prone = He will just keep getting worse.
The WWE would be smart to depush Batista after WM before he gets injured again. He still has a little star power left in him so he should be used to put over people who have a future. After losing to Taker he should job to Kennedy, Helms, Orton, Cena and Edge before finally going off into the sunset quitely.
Batista was a terrible wrestler to begin with but at least he looked somewhat strong. Now he is just a terrible wrestler who looks weak. He can't fall back on any technical ability, because he has none and its too late to send him back for training now. Get what you can out of him then cut your loses.
Pre injury Batista was great he wasnt amazing but great now he isnt that good he just has the body but his moveset is slightly better than cena's
You might want to take that back. Batista has four moves ( Spinebuster, Clothesline, Batista Bomb, Turnbuckle shoulder block) and not one of them looks credible. I'm telling you he is going to kill someone in the ring. He could barely lift Kennedy. Add in the fact that he gets tired in tag team matches and can't work a 5 minute match by himself and the gap between Cena and Batista is even wider.