The Baggies - who kick off their Championship campaign at Middlesbrough next weekend, secured a 2-1 victory over Hertha Berlin in their last pre-season friendly of the summer.
Bruce started the game against the Bundesliga side with a front four of Matt Phillips, John Swift, Jed Wallace and Karlan Grant.
But it was substitutes Grady Diangana and Daryl Dike who were instrumental for their two goals.
Diangana set up Swift for Albion's equaliser with Dike then going on to net a brilliant header from an excellent Wallace cross.
And Bruce was pleased with what he say from his forward players.
"You’re only as good as your forward players, and today they changed the game for us a little bit," he said.
"Let’s hope I can make a few more substitutions like that work.
“We’ve got a bit of quality at the top end of the pitch, which is why we brought in Swift in particular, and Wallace.
"They’ve scored one and made one. We had to improve in that area, that was our Achilles heel.
"We created enough but we never scored enough. We relied too much on Granty last year.”
Albion's other friendlies this summer have been against sides in League One or League Two.
And they fell behind against Hertha Berlin - with the Germans scoring an excellent team goal that was finished off by Davie Selke.
And Bruce felt the game was a good test for his side.
“No disrespect to the teams we’ve played, but it’s a step up in quality and you could see that," Bruce added.
"They’ve scored an unbelievably good goal in the first half.
"Wow, what a goal it was. I felt like applauding it.
“They’ve got some good players who have been around the block and who have played at the highest level.
"We knew it was going to be difficult, and it was, but it was a good work-out for both teams.
“Overall you’re looking at it, the three or four that we brought on - which is going to be crucial in this Championship race - gave us that bit of quality which sometimes you need.”