28-32 is past prime for most real world footballers, though there are exceptions. 24-29 depending on position, with Gk peaking later, attackers slowing earlier. Here's some analysis from world cup history: When do footballers reach their peak? - BBC News

Nordeus advises a mix of ages. Personally, I bought a striker 2 seasons from retirement who didn't play well, but do have a retiring DL who was very effective from 30-33.