Stamina in lower rep leagues

I have always wondered why the stamina of most players in leagues with lower reputation is so low. Take for instance my team FC København from the danish Superliga. In the game most of the players can barely play the first half of a match without needing resuscitation. Why is this?! In the real world FC København have no stamina problems when playing in the domestic league or the european matches against the big teams (Man Utd and so on), so why is this the case in the game?

It could be partly due to inferior training facilities. Also, many lower league players are technically good enough to play at a higher level but just don't have to stamina to cope. Have you lowered the tempo and closing down to preserve their condition?

Maybe it's a research issue? Players from lower rep leagues get have lower CA and without their attributes being properly balanced they just get low stats at everything. I can't see any Nordic player having stamina less that 12