And he knows that a repeat show at the Hawthorns would see his side's chances of claiming one of the two automatic promotion slots further diminish.
Jewell said: "We were poor at Bradford and will finish out of the top six playing like that.
"That wasn't the real Wigan out there, the real Wigan are a competitive outfit who try and get the ball down and pass it.
"Tomorrow night is the game which counts now and it should be a smashing atmosphere at the Hawthorns.
"We will have to compete better than we did against Bradford because West Brom are a physical side.
"I think the players knew they were disappointing on Saturday, and if they didn't, I made sure they did in the dressing room afterwards."
While the draw at Valley Parade saw Latics move back into third place, the gap between themselves and the Baggies is now nine points.
So they could do with a maximum haul of points from their visit to the West Midlands to keep their rivals in sight.
Latics never looked like winning Saturday's game, which saw Jewell returning to the club he served as a player, coach and manager for 12 years
And Jewell went as far to describe the display as "rubbish" with him pulling no punches.
He said: "We were rubbish from start to finish and that won't get us anywhere near where we want to be.
"We had one decent shot on target in the whole 90 minutes and I can't hide behind that performance.
"The lads were terrible and the only two good things about it was that we got a point and kept a clean sheet.
"I didn't think Bradford were great by any stretch of the imagination but they were better than us on the day.
"Their 4-3-3 system is hard to play against and they're fighting for their lives.
"Okay, the pitch was bobbly, but we never competed as well as we normally do.
"The boy Paul Evans two-footed Jimmy Bullard in the first minute and that seemed to set the tone.
"It seemed to shock our lads and that was disappointing.
"Anyone watching that game wouldn't have thought Wigan were where they are in the table. But that's football and you don't always get what you deserve.
"Last week we got beat with the last kick of the game by Crewe after being great, and on Saturday we were rubbish and got a point."
Jewell handed a debut to Gareth Farrelly, starting him on the left-wing in place of Alan Mahon who failed to shake off a hamstring strain.
But he replaced him with Neil Roberts at half-time, citing Farrelly's shortage of match fitness as the reason.
"I didn't really want to put him straight in but I didn't really have too many options," said Jewell.
"I wanted to leave Lee McCulloch up front because he got two goals last week.
"Alan Mahon tweaked his hamstring so we couldn't play him, so I tried to give us that balance by putting Gareth out there.
"But to be fair to him, he is somewhat off the pace at the moment.
"We have missed the power of Jason Roberts and the pace of Gary Teale, but we have to get on with it.
"On Saturday, I thought the service up to Nathan Ellington was poor, and when he did get the ball, he could have done better.
"But the whole team as a unit didn't perform and Bradford put us under pressure.
"They got in our faces and tried to do to us what we normally do to the opposition.
"It was another point gained but not a satisfactory performance by a long stretch."
Source: Wigan Evening Post.