Remove the wrestle skill, now there are two skills: Block(1) and Block(2). Block(1) can be upgraded to Block(2) in place of a General Skill, this is the only way to get Block(2). If a player has neither, they are assumed to have a Block(0).
Outcome of both down result:
- One player has a block skill level exactly 1 higher than the other: The player with the lower block skill is placed prone.
One player has a block skill 2 or more higher than the other: The player with the lower block skill is knocked down.
Both players have the same block skill level: Both players knocked down. If the attacker has Block(2) or higher, both players placed prone. If the defender has Block(1) or higher, his/her coach may choose for both players to stay on their feet.
and the part that makes all this interesting (and deals with unknockdown-able players):
When a player makes a blitz action, they are treated as having a block skill one level higher for any blocks they throw.
with a couple of minor changes to skills:
Fend: In addition to preventing follow-ups, a blitzing player does not receive the block skill bonus from making a blitz action.
Juggernaut: As standard rules, fully cancels the new Fend skill above as part of a Blitz action. Wrestle does not exist.
Now we have a much more varied blocking landscape!

Every player that currently has Block would have Block(1). I'd be tempted to give Dwarf Blitzers Block(2) and hike their cost by 20k, to make the team a bit more interesting. Chaos might suffer for how far behind they are on the Block skill progression. Big guys would get a little better as now they can effectively Blitz with Block(1).
This can probably be filed in the same folder as "should we replace the d6 with the d12?". But I welcome any feedback to improve the idea.