He should be increasing his protein intake and eating whole foods. The assumption that salad is good for you has to stop. The common America salad is full of bad fats and bad carbs mostly because of the highly processed cheese and dressing they use.
He’s a professional athlete that should be both weight training and performing in game. So he needs a source of lean protein and healthy carbs and fat.
His issue is probably strictly portion sizes and snacking. Cuts that out the weight will fall off and he won’t have to restrict his diet that much. You can eat plenty of good tasty foods while maintaining a calorie deficit. I don’t think he should be in a deficit during the season but he should learn his maintenance calories. He’s so overweight he would probably lose a lot of weight regardless.