Just to wade into this, more as an ex keeper and with a goalkeeping son (8)...
Spoke and watched a training session dealing with crosses.
Common misconception that the knee is there for protection...
Think about this... a high jumper wants to get to maximum height... do they run up and use both feet?
The goalkeeper has the same principle... the leg being raised is for leverage... just like the player elbow for natural jumping leverage..
Fine when no player next to them...
Likewise with a keeper --- a great take to and empty box...
Put a player next to the elbow or player in the box for the cross...
It's almost like you need a neutral to decide if the challenge is fair
Spoke and watched a training session dealing with crosses.
Common misconception that the knee is there for protection...
Think about this... a high jumper wants to get to maximum height... do they run up and use both feet?
The goalkeeper has the same principle... the leg being raised is for leverage... just like the player elbow for natural jumping leverage..
Fine when no player next to them...
Likewise with a keeper --- a great take to and empty box...
Put a player next to the elbow or player in the box for the cross...
It's almost like you need a neutral to decide if the challenge is fair