ST KILDA coach Ross Lyon last night lamented a 31-point loss to Essendon and yet another hamstring injury, this time to defender Sam Fisher, as he said the club's fitness regime could be to blame.

Lyon was also baffled by the decision to leave the Telstra Dome roof open during a rainstorm, ensuring a wet and slippery surface.

"It's interesting, isn't it? It's interesting to walk in at 12 o'clock and see the rain coming down and the roof's not shut. I suppose you have to look at the aim and the agenda of clubs and the stadium and the AFL, what you want to produce, I suppose what sort of spectacle."

It is believed that ground officials notified the AFL, which decides on the closure of the roof, of approaching rain more than two hours before the 2.10pm start. A decision to close it was made at about 1pm.

AFL spokesman Patrick Keane was unaware of the issue, but said the incident would likely be brought up in the AFL's weekly review.

Fisher left the field in the second quarter and the extent of his injury is not known. In recent years, the club has had plenty of hamstring injuries.

Lyon said their new fitness expert, Peter Mulkearns, had gone over previous fitness regimes and found an important component was missing. When pressed, Lyon said the actual thing missing was the humble squat exercise.

"The meat and potatoes is there hasn't been much squatting in the program. Meat and potatoes, that's what's missing — it's a basic. You can laugh, but if you're not doing it under the extreme forces of AFL footy, something's going to give and it seems to be the hamstring."

Essendon's Jason Winderlich was a late withdrawal with a hamstring injury, while Leroy Jetta will miss Wednesday's Anzac Day clash due to a groin injury. David Hille, who took a knock to the chest, is in doubt.

Lyon played down the hard spoil on Luke Ball by Dustin Fletcher that left Ball prone. "It wasn't a great kick to him, was it? … he was cleared to play; he wasn't concussed. He'll be better for the run."