This is a known and reported issue to the development team. Until a Title Update patch fixes the issue, when starting a new Manager Career mode save, always select 'Only Manual' for the training program. Choosing either 'Manual + Automatic' or 'Automatic' results in broken stamina levels or sharpness in-between matches. Have not experimented with the settings to determine if a coding error has reversed the instructions, or the entire system requires recoding. To avoid problems for now, manually set the training plan to 'Performance' (not sure of the technical name, one setting below all out performance) on the first day of a new career save, and alter the plan to default or energy when playing three matches in ten or eleven days. For a normal schedule (one match per week or two matches in ten days), the performance training plan will suffice.
Manual training plans still has a fitness bug. I set all my players to regain 100% fitness before the next match, then when the next match day comes around a handful of players have less than 100% fitness. It even happens when there's a week between matches.
Still not fixed in any of the title updates either.
