Former Australian Sports Anti-Doping Authority chief Richard Ings said on Tuesday the anti-doping body had judiciously carried out its process of collecting the A and B samples from the Fremantle tagger, in which he has tested positive to a banned pain-killer and has been provisionally suspended.

Crowley was informed of his positive B sample and handed a show-cause notice on September 18, and accepted a provisional suspension on September 25.

However, a hearing before the AFL anti-doping tribunal has yet to be confirmed.

It's understood that Ian Prendergast, in charge of player relations with the AFLPA, was seeking an explanation from the AFL's integrity department head Brett Clothier over why a hearing had yet to be convened.

PA chief Paul Marsh said clarity was needed.

"We are still trying to get a full understanding of why that is. But the club and the player are certainly comfortable with the process to this point, so I don't think there are any huge concerns from where we sit," he said.

AFL anti-doping tribunal chairman David Jones has been involved in the hearing over alleged banned drug use by 34 past and present Essendon footballers since December last year, and will deliver his verdict on March 31.

Ings said the AFL needed to explain its version of events.

"I have been following ASADA closely for a number of years and I have to say the time ASADA has taken for the process ... is pretty quick compared to what they have done in the past," he said.

"Where I think you have the overlap is more with the AFL. The AFL issued the infraction notice on October 1, normally an AFL tribunal would convene very quickly, within a couple of weeks, but with the Essendon tribunal going on, perhaps the AFL can't run two AFL anti-doping tribunals simultaneously.

"Once a sport issues an infraction notice, there should be a hearing without delay so the matter can be resolved. We are in March now and we still don't have a date for a tribunal when the infraction was issued in October last year.

"I think the AFL needs to give an explanation. The AFL did a pretty good job in putting out a detailed time line [on the Crowley case], when the sample was collected, when the A and B was completed, when the infraction notice was given, but it stops on October 1 when the infraction notice was given by the AFL.

"What has been happening at the AFL in the last six months in causing delays that this tribunal has not been convened?"

It's understood Crowley took the pain-killer in the days leading into the round-17 clash last year against Greater Western Sydney.

It's believed the AFL will look to broker a revised agreement with ASADA when the Essendon case is completed.

Crowley's A sample was taken on August 11, with the B sample taken on September 11. Crowley, though, was still able to play in the Dockers' losing semi-final against Port Adelaide two days later, before the show-cause notice was issued a further five days later.

The original sample had been given on July 13 but wasn't tested for another 29 days, adding to debate over the length of the entire process.

Speaking on Radio Sports National, Ings said ASADA had completed its mandatory processes around the A and B samples quicker than in previous cases.

"When ASADA takes the sample, it's one of several thousand ASADA will take per year that is sent to the Sydney laboratory. That laboratory, unless they are particularly asked to expedite the sample, will normally take about two-to-four weeks to return the A sample alone," he said.

"Then you have got to notify the player of the A sample. Then you have got to organise a date which is convenient for ASADA and the player and the lab for the B sample. The player needs lawyers. There are steps to work through, so a 10-week time frame to complete the A and B is pretty normal and indeed pretty fast for ASADA in this case."