Analyzing market value drop

I want to focus on a general analysis of why this player's market value might have dropped. Factors include age, injuries, and a role change, which can affect perceived value. His peak performance was during his time at Liverpool and early Barcelona. Injuries and inconsistent playing time also play a role. It might be worth explaining what "市场价" means in the context of valuation. I could suggest a deeper look into his career arc or comparisons with similar players for further insights. What specific analysis or options are you interested in?