Solanke battled to get involved in the defeat to Arsenal.
Postecoglou said afterwards: "I thought Dom worked hard but, like I said, he hasn't played for over a month, only his second game of the year.
"I just thought there were a lot of odd times where, you know, if we just had a bit more belief and conviction in that front third that we could have made so much more with our play to create really good opportunities and, and even the ones we did, you know, we didn't again, like I said, we lacked some real conviction in their execution to really make the most of them."
On the team's lacklustre attacking form, the manager added: "We've just got to keep working at it mate, that's my job. I've just got to keep giving the feedback to the guys, trying to guide them in the right way to make them see that for all their dominance in the game, you need to really be clear-headed in those kind of moments and, that's my role to try to guide them in the right way."