Hi there, from someone who has played half a dozen tennis games I love the gameplay but had a suggestion: it would be really cool to be able to integrate prize money into the experience. Eg it costs money to travel to tournaments so you are really incentivised to go deep in them and have the potential to lose money if a tournament doesn't go well. It would also create great dilemmas such as should you try to slog through grand slam qualifying early in your career to get a shot of that sweet prize money or stick to futures for reliable steady income. You can hire support staff to slow skill degradation or give bonuses to recovery etc. Maybe injury and paying for surgery and rehab could be a feature. Maybe exhibition events where you can get a fair amount of money for an appearance fee but you lose out on the ranking points you would otherwise get for an ATP tournament.
It would really deepen the career mode which is a little unsatisfying atm. Of course sponsorships could be included as well but the complexity to implement and balance that is far higher than the stuff mentioned above so probably not worth it. I know you also make tennis manager games so imagine some of the logic is already coded. Maybe you are worried about cannibalizing sales from the manager series but IMO making tennis elbow 4 a better more complete game will draw more people into the franchise. Needless to say I know far less about game development than you so maybe my ideas are completely unworkable. Just wanted to share my thoughts.