A CLOUD has descended over Essendon's players in the wake of the World Anti-Doping Agency reopening the investigation into the club's 2012 supplements program, coach James Hird says.

The Bombers have lost three of their past four games since WADA's announcement in early May that it was appealing the AFL's Anti-Doping Tribunal's not guilty verdict on 34 current and former Essendon players.

"The players have been through such a journey … that the cloud has come back over them," Hird said in an interview on Triple M on Sunday.

"They don't specifically run out there thinking about WADA, but when you go through a journey like these guys have for two or three years and then you know this journey has got, maybe another year to go, it makes it harder rather than easier to play AFL football."

Essendon slipped to 4-6 and 12th spot on the ladder after a demoralising 69-point loss to Geelong at Etihad Stadium on Saturday night, failing to register a goal in the first half.

The Bombers now have season-defining clashes against the resurgent West Coast and back-to-back premier Hawthorn to come, with the bye sandwiched in between.

Hird said the resilience of the Essendon players was being tested like never before.

"It's not faltering, but it does get tested everyday. These players have gone through something not many have, but they've got to go out and perform week-in, week-out because that's what the game demands," Hird said.

However Hird stopped short of declaring the WADA investigation as the primary reason behind the club's form dip.

"Once that decision came down after the Fremantle game we probably have taken a few backwards steps," Hird said.

"But it's no excuse for what's going on and Essendon supporters don't want to here about WADA and ASADA anymore and to me, and this is what we spoke about after the (Geelong) game as a group, the only way out of what we're in is winning games of football."