The Baggies headed to Deepdale having struggled to break down both Millwall and Derby in their previous two outings.
And that pattern continued in Lancashire in a match lacking in creativity throughout.
North End opened the scoring midway through the first-half when Ben Whiteman saw a strike from 20-yards deflect past Sam Johnstone.
Matt Phillips then pulled the Baggies level just seconds before the interval when he turned the ball in following a Darnell Furlong long throw.
Albion did have a good chance to win it late on through Jordan Hugill.
Overall, though, they created very little.
In each of Albion's last three games, their opponent has played direct and long to ensure Ismael's side can't impose their high pressing game.
And the boss admitted his team hasn't been good enough when it comes to taking chances and creating them.
"I think it was the same picture as against Derby - it’s as simple as that," Ismael said when asked to sum up his team's performance.
"The opponent had two shots on target and scored a deflected goal.
"They took the lead, we came back into the game just before half-time which was really important - it gave us some momentum.
"In the second half it was exactly like Derby.
"We tried everything, we showed the right mentality. And that is the good thing.
"What we have seen is that we need to work more on the last third.
"The problem is the quality of the last pass, the quality of the cross - it was not good enough.
"And when you get a chance to score you have to take it - we have to develop that killer instinct.
"That is the last step that we need to do working with the guys - to win games you need to score.
"We create chances, we had a big chance to score and we need to develop that killer instinct.
"But this is the Championship. You see the result today, a surprise result.
"It’s one of the toughest leagues in the world.
"Just because you have dropped from the Premier League, you’re not going to drive on the motorway and it’s a freeway for promotion.
"It’s a fight, we need to take the fight.
"It’s early in the season but we have a clear picture of what is going on against us."