"We got what we deserved", said Brewer, whose men have won both domestic home games but been beaten twice on the road so far this term.
"I can spin a load of rubbish to you as far as us being a maturing side. But if individuals go out on to the field and they're not committed and haven't got the attitude to tackle, the opposition will run through you.
"One of the key things I'm trying to install in this side is attitude and to never give up. It was really disappointing."
The manner of the loss at a Bath side who had themselves been heavily beaten by Northampton the week before has left Brewer with serious concerns prior to the start of European competition in a week's time.
"There's a few individuals in there who are a bit brittle", continued Brewer.
"We've got to take them to the side and talk to them. Sometimes that mental weakness is due to a technical issue.
"You lose it mentally, like a golfer on the putting green or on the tee box. Technically we've got a few issues and we need to address that and bring those players on. There were a couple of players out there who won't be playing first-team rugby for a long time until they start improving those technical issues for the 80.
"We've basically played 120 minutes out of the season so far - 33 per cent. We're inconsistent as a team and that's the message I tried to give to the guys.
"There are very few players in the world who can turn up on the Saturday and perform. You've got to perform in training throughout the week.
"When you're up and down in training you'll be up and down in the game. Consistency in performance is what it's all about."
Sale begin their European adventure at home against Cetransa El Salvador, before making the trip to Petrarca Rugby and Brewer is hoping to welcome back some key players in time for those games.
Charlie Hodgson is expected to feature against London Wasps in the Premiership on Friday while fellow England international Matthew Tait could be fit the following week.