Is there an alternative to "that much less"?

• all the more unfair
• even worse
• that much more unbalanced
• more unfair still

They still feel kind of awkward though.

I don't know if this is considered rephrasing, but I think the culprit is the weak verb "made":

The teams weren't fair to begin with, but Jim's injury exposed their treachery.

or

The teams weren't fair to begin with, but Jim's injury brought them to a new low.

You could try

The teams weren't fair to begin with, but Jim's injury made them still less fair.

or, to avoid repeating fair:

The teams weren't equal to begin with, but Jim's injury made them still less fair.

or even

The teams weren't equal to begin with, but Jim's injury made them unfairer still.