It comes down to a combination of factors.
Firstly there's no doubt they've hit a wall. Reynolds is struggling with a rib, back and injured hand. He really shouldn't be on the field but it's the pointy end of the season and the team needs him out there. What's happening is he's putting himself in these poor positions since teams are really going after him and he's getting caught with all these accidental contacts. Throw in injuries to Capewell, Haas, Farnworth, Cobbo, Brenko, Flegler, Kobe, Ezra etc and they've just lost several steps that made them so competitive.
Like Melbourne, these injuries didn't just occur to the top line player but the depth players as well. Prospects you'd be hoping to bring in like Paix, Robati, Piakura etc. have all been affected and haven't been able to get the runs on the board to come in and provide those options.
As an aside, I think fans are being harsh to suggest Hosking was let go to keep Riki. Riki, Piakura, Capewell and Robati all signed long term before Hosking was even at the Seagulls. He's been a quality depth player but it was never a case of Sophie's Choice and it doesn't appear he's an option at 13. He played OK, but still think he's a depth option.
On top of battered players, the fill-in players really struggled. For mine the contest lasted about 15 minutes. Brisbane had a few opportunities to make their mark and they were just found out and it was the fill-ins in the middle of it. Pereira got exposed against Sivo, Walters filling in for Reynolds gets pinged on a forward pass (don't start me), Turpin with the strip, Brenko with the defensive error that leads to the Mam penalty etc.
To be clear it's not on them and that Staggs penalty from the kick-off was poor as well but those little moments make a huge difference in this era of momentum. In the end, Parra had all the ball and Brisbane were rudderless thanks partially to losing their captain 12 minutes into the game.
The other is that they still have to improve in a lot of areas and I'm not sure if their roster or coach is capable of it. Obviously defence is a key concern, they struggle to get their counter-parts on the ground and just lose far too many rucks. Line-speed at times is non-existent and players are either unfit through bad cardio or injuries to be in the right position. I like Kobe's technique, but he seems to struggle with the cardio demands and the only other player I really rate is Carrigan who has clearly improved that area. The rest all need work and they'll have to take it up another notch this pre-season.
There's a lot of areas they need to work on. Really if they want to make finals and draw some kind of silver lining it's on the line next week. Personally I don't care and I've been ready for Round 1 2023 since Walsh signed but I know it'll improve the mood and their confidence if they make it and put in a decent showing.