I've said it before and I'll say it again, I wonder if the training is the reason for so many injuries. Now, I'm no expert on fitness coaching but perhaps there are procedures and things they are doing every day that are detrimental to their condition.
Now, this is where a possible new signing could come in. There is a well known fitness coach named Steve Black who is widely regarded as one of the best coaches and motivators in the world. He's worked with Sunderland, Newcastle, Huddersfield, the Welsh rugby team and most notably he's credited with training Johnny Wilkinson, along with many others. Apparently his injury record at Huddersfield was one of the best in the game and is supposedly due to some of his "revolutionary" ideas to fitness. Perhaps making a move at signing him, would be better than any player.