INJURED West Coast key defender Mitch Brown says he is not surprised by how well the injury-ravaged Eagles' defence has held together this season.

Brown tore his anterior cruciate ligament in the opening quarter of round one against the Western Bulldogs, while Eric Mackenzie did his in the Eagles' first NAB Challenge match against Carlton, both players being ruled out for the season.

There were grave fears for West Coast's season after their two senior key defenders required knee reconstructions, but the Eagles defence is ranked fourth in the AFL for scores against, and the club sits third on the ladder after 10 rounds.

Brown said the success of the patchwork defensive unit has been a source of pride this season.

"From my end, (it's) no surprise," Brown said on Wednesday. 

"At the start of the year we lost 'Easy' (Mackenzie) and then myself, and it did look a bit shaky.

"But with (Jeremy) McGovern and (Will) Schofield there, I couldn't be prouder of the boys. They're playing some really good footy at the moment and they're playing as a unit. They're helping each other and finding a way."   

Brown said it has been a tough period watching the team from the sidelines after undergoing the second knee reconstruction of his career.

"Initially I had a little cry in the change rooms, but I moved on pretty quick and I've kept pretty positive," Brown said.

"I'd be stupid to think I won't have my ups and downs. I've had some downs, some low moments in the last 11 weeks.

"But I'm keeping positive. My rehab is going well and I've just got off crutches. Actually walking around is a big milestone for me, and it just makes a lot of things easier. So my wellness levels are right up now."

Brown's first knee reconstruction was in 2008, and the 26-year-old admitted he could hardly remember what the rehab process was like.

"A lot of techniques have changed," Brown said.

"A little bit of the surgery has changed. But it kind of helps to know what I'm in for and things like that.

"It's never good. It's 12 months out of the game you love, and I can't get out there and enjoy the good form the boys are in at the moment. I would love to be out there playing with them."

Brown said that he and Mackenzie had formed their own rehab group for the 'warhorses', adding that Mackenzie was progressing very well.

"I think he's about four or five weeks ahead of me," Brown said.

"But he's going really well at the moment. He's cycling. He's doing a lot of stuff. He's got over that initial stage of having no exercise and he's slowly getting fitter and fitter and he's in good shape, considering, at the moment."