Fredi, whose appearances have been restricted by hamstring and, more recently, thigh problems, makes only his 11th start of the season against Liverpool, and John says: "It is probably best for the medical staff to comment on it but they are happy for him to play which means they are happy with the condition of his hamstring.
"He is modifying his training slightly to allow for his style of play and hopefully prevent injury in future, but I think he has been unfortunate and it is not for lack of treatment or effort on his part.
"He has got phenomenal strength; his long limbs and the way he plays are factors we have to account for.
"There is only so much you can do and he knows that he has to put the work in which he is doing.The medical staff are very happy with his progress and are continuing to work with him."
John feels that there has been a good response to his full time appointment in the summer, and he says: "Certainly from a fitness perspective the lads are doing very well indeed - all the statistics and measurements we have taken show they are on top of their fitness and in the target zone we want.
"In fact they are improving through the season; this is a time when traditionally it does tend to peak and drop off, but we certainly don't want that happening.
"The training methods we employ don't, we hope, induce any injuries and we have to be careful to train them to sufficiently improve their fitness and maintain it, but not so as to push them over the edge.
"It is a difficult game, but the coaching staff use very good methods - sometimes it is down to the luck of the draw.
"I think they have taken on board wholeheartedly the new regimes for hydration and diet, and we are hoping this is the way forward.
"There is a short turnaround between games and the players have responded very positively; they are meeting the right targets, eating the food, and drinking the right amount of drink.
"For myself I think this is a time when we are peaking; the players are reaping the benefits of a good training programme and excellent coaching."