Two goals in the first 10 minutes from Tom Lockyer and Alex Rodman, as well as a Tareiq Holmes-Dennis strike, saw the Gas run out 3-1 winners on Boxing Day.
Despite being on home turf, Walsall never got going with Keates admitting his side lacked quality all over the pitch.
And he said the result, against a Rovers side who started the day in the bottom four, means Walsall are now battling to stay in League One.
“We have got to find a level of consistency,” the boss said.
“I've told the players I am sounding like a broken record.
“Yes, we are a young squad, but we have to grow up and we have to grow up quickly.
“We had an opportunity to go 14 points clear of a club that is fighting for their lives.
“Now we are only eight. We have put ourselves in a relegation battle - there are no qualms about it.
“I've said from day one, it's about getting to 52 points as quickly as possible.
“But that performance has left us wide open and now we have a game against on Luton on Saturday who are the most form team in the division.”
Walsall remain 10 points clear of the relegation zone.
But when quizzed if they are in a fight to stay in League One, Keates replied: “To an extent we are battling to stay in the division.
“We are one of the smallest clubs in the league. But teams are not earning the right to score against us. We are giving silly goals away. That has to stop.”
Walsall beat Bristol Rovers 1-0 back in October when Kieron Morris netted a 90th minute winner.
And caretaker boss Graham Coughlan revealed the way Saddlers’ players celebrated that win gave his team added motivation heading into today’s clash.
“We recall we played them at our place and they came banging on the manager’s door and running down the corridor as if they had won a World Cup,” he said.
“I ain’t going to let things like that happen to this club and we’ve come here and we’ve got, I would say, our just rewards.”