The Uruguayan picked up a groin injury in training last Friday, and received treatment throughout the hours leading up to the Southampton game on Saturday, but couldn't make the squad.
The interim manager described Edi's problem as a minor muscle injury, but said that it was pointless to risk players when a scan revealed an issue.
“It is always sad if you have players unavailable, no matter if it is Edinson or another,” began Ralf.
“If they are injured, they are injured. If a player says he is not available because he is injured and we do a scan, and realise there is an injury, even if it is a minor muscle injury, if the player says he cannot fully sprint it makes no sense to have them in the squad.