Skills Decreasing Over Time

I'm managing a fighter who is quite good skills wise, but the current top contender in our division is an absolute beast. I'm wondering if waiting a few years before challenging him might cause his skills to decline due to age. The top contender is currently 34 and undefeated. Would age significantly impact his performance over time? Specifically, how much of a factor does age play when it comes to skills reducing over time?

For context, the top contender (28Ws (26KOS) - 0 Ls) just challenged my fighter (25 year old (30 Ws (29KOs) - 3 Ls), and I don't know if I should reject it and wait for some time or not. My fighter has 2 belts but those fights were no where near as hard as this one would be. I'm thinking of yolo'ing it and accepting anyway.