Bruce was pulling his hair out after seeing his side punished for their costly misses in Saturday's defeat at the Hawthorns.
The one bright note from the 3-1 reverse was Hugo Rodallega's first goal for the Latics, but that aside, the Wigan boss was less than pleased with his troops.
"We've made too many mistakes," Bruce told Sky Sports
"But we've had enough chances and if you don't take them at this level you don't get too many more and that's been our Achilles heel."
When asked if that was down to the lack of confidence with his forwards, Bruce added: "I'm not just blaming my forwards - it's everywhere.
Frustration"We've had chances all around today but we've created enough in the first-half and played well enough to be out of sight really but it's not to be and that's been the frustration."
There was further misery for Bruce as both goalkeeper Chris Kirkland and substitute striker Amr Zaki were forced off the field with injuries and the Latics boss felt like salt was rubbed into the wound.
"That's going to take time," Bruce said of Zaki's injury.
"Chris - it's that reoccurring back problems but with Amr it looks, or what I've seen anyway, like one of those horrible cruciate ones so we'll have to see with scans and X-rays over the next 24-48 hours and know a little bit more then."