All true, but Wenger doesn't mention that here:
"I can tell you he has been everywhere in the world to be assessed. There is an explanation. He is quick, strong, has good stamina, good resistance to repeat, but his muscle strength is not good enough to deal with that. Sometimes little fibres go in his muscles, this is basically his problem.
"When you play every three days, you cannot rebuild your strength as you need to recover. When you don't rebuild your strength, through the games you burn your fibres a bit and become weaker and weaker, so that means he gets injured.
"The second reason for his problems of course is his ankle.
Since he was slaughtered at Sunderland, his mobility in his ankle has been affected."
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Arsenal boss Arsene Wenger alarmed by Abou Diaby fitness problems | Football News | ESPN.co.uk