The Cottagers won 3-2 at Turf Moor, with Parker conceding the courageous defeats are beginning to grate.
He said afterwards: "It's frustrating, it's disappointing. I've stood in front of you guys for the 16 games so far with the same message.
"It feels like deja vu. It feels like I'm saying the same things every week. It's the same cycle.
"In this division you can't afford to give away goals like we have. We were competitive. But we gave ourselves a mountain to climb.
"We had a mountain to climb in this league. The mountain isn't huge for us. It's just a tiny bit (we need to fix)."
On the goals conceded, Parker continued: "It's an element of concentration and focus. It's a deadly league.
"One lapse in concentration and nine times out of 10 it's in the back of the net.
"The cold reality is that - at this moment in time - we're making life difficult for ourselves, and we need to fix up on that."