COLLINGWOOD's Alan Toovey has come to the defence of embattled teammate Harry O'Brien, saying the team has contributed to the defender's disappointing form. 

O'Brien has started the season slowly and was easily beaten by Hawthorn's Cyril Rioli in round one and Eddie Betts in round three.

Toovey said his backline comrade had struggled as a result of the team's lack of defence in other areas, and backed him - and the injured Dale Thomas, whose form has also been down - to respond.

"It's more of an indication of the way the team's defending rather than one individual," Toovey told AFL.com.au on Thursday.

"When your team's not defending well, it's easy to kind of pick out single players whose opponents are kicking goals but really, you want 18 people defending. It's a goal against the team, not one player.

"Harry and Dale are both great players for us and just because they've had a slower start to the season, I'm sure they're going to bounce back because good players always do."

Toovey said injuries to Chris Tarrant and now Ben Reid had fast-tracked the development of Lachie Keeffe, who has given himself a strong chance of holding his spot even when the backline is fully fit.

He also said the imminent return of Nathan Brown and the resurgence of Martin Clarke had been positives.

"Nathan's had to work really hard to get through all that rehab, and he's done a really good job of it," he said.

"He played a whole game through the VFL last week and said his body felt really strong, which shows how much effort he's put into the rehab to come back and play two VFL games and be feeling really good.

"Even having Marty come back and straight in for round one, he's covering a lot of ground, so they're good points to take out of it."

Meanwhile, Thomas has explained how he and Heath Shaw hurt their hamstrings this week, which are expected to cost them the next two games.

"I just twinged a hammy late in the game [against Carlton], it was just a little bit sore, and then I tried to train on Wednesday and just couldn't go a yard, so I had a scan," Thomas told Nova FM on Friday morning.

"Heath hurt his about half an hour later at training on the Wednesday.

"I'll hopefully be back bigger and better."

The views in this article are those of the author and not necessarily those of the AFL or its clubs.

Jennifer Witham is a reporter for AFL Media. Follow her on Twitter @AFL_JenWitham.