.3 of a year average of age difference when comparing 2 leagues with thousands of players between them is literally just noise. It's like saying the two leagues are exactly the same age.
Secondly, using the echl as evedince of "pro" career is a joke. It's a glorified beer league. If you're playing in that league your either young enough to hope to one day play in a real pro league, or hockey is basically a hobby for you. At that point you probably should of went to culinary or trucking school.
Thirdly, virtually all the players that do go on to play in the Ahl or Nhl from the Ushl don't go straight to pro hockey. They go to the Ncaa and then go pro. Obviously, Chlers don't have an intermediate college step. They go straight from the Ohl to the Ahl or Nhl. The implications of that difference should be so obvious as to not need further explaining.