Talk Fantasy Football

On page 52 in the LRB 5.0 a wizard can be used at the start of my own turn before any players performs an Action or immediatly after my team's turn has ended.

If my wizard will cast a fireball or a lighting ball after my turn has ended and the ball carrier of my opponent will lost the ball because he is falling down - does this count as a turnover for my opponent and my team has just another turn to play?

Or means that, that the ball carrier lost the ball at the end of my turn?

No TO for opponent. His/Her turn has not started yet. Before the opponent's turn starts you need to resolve all rolls (ball bouncing, armour, etc) after your effective TO or ending your turn voluntarily. Howerever your opponents turn doesn't start until all other things are resolved.

So basically a turn starts when you take an action with a player or do something else required before the actions are taken (such as a wizard or card effect)

It is not a turnover as the event happens in between turns (that also means no team rerolls for either team).

THX