The opening batsman and skipper has hit three half-centuries in this year's edition of the Twenty20 tournament but his runs have come at a sluggish strike rate of 114.83.
At his explosive best, the left-hander is a match-winner. He boasts a strike rate of 141.30 in his 99 T20 innings for Australia.
But he cannot get going in this year's IPL and his snail-paced 51 runs off 47 deliveries in Tuesday's last-ball loss to the Mumbai Indians did little to quell concerns about his decline.
The once-destructive Australian appears laboured, even nervous.
"Even in the last couple of games, when he has been trying to hit, it's not been coming off," deputy skipper Axar Patel told reporters after the agonising defeat to five-time champions Mumbai.
"As a batsman, I don't know what he is thinking at that moment."
Warner's innings got a boost in a 67-run sixth-wicket stand with Axar, who smashed a 25-ball 54, but Delhi were all out for 172 and their opponents went on to win by six wickets.
Delhi are bottom of the 10 teams in the IPL and the only side yet to win a match.
Axar said that Warner has spoken to Ricky Ponting and Shane Watson, two Australian greats on Delhi's coaching staff, as he bids to get firing again.
He has also been counselled by former Indian Test captain Sourav Ganguly, Delhi's director of cricket.
"The conversation about his strike rate also came up. They looked at his videos and he's working on it," said Axar.
Pundits have been scathing in their assessment of Warner's struggles.
"I feel it is time that we tell him in English now so that Warner listens to it and feels hurt," former India opener Virender Sehwag told Cricbuzz after the weekend's 57-run loss to Rajasthan Royals.
Warner made 65 in 55 balls before Delhi went down tamely in their chase of 200 in Guwahati.
"David, if you are listening, please play well...If you cannot do that, do not come and play in the IPL," said Sehwag.
Renowned commentator Harsha Bhogle responded to Tuesday's knock from the veteran opener by lamenting how difficult it was to watch "the great David Warner struggle".
The Australian had been a drag on the team, Bhogle said.
"He has been very honest about it, but at the moment, it isn't helping DC get the momentum they need," he wrote on Twitter.
Delhi, who have never won the IPL, are now in danger of an early exit from the play-off race.
The franchise suffered an early blow when skipper Rishabh Pant was involved in a car crash in December and was ruled out of the season, propelling Warner into the captaincy.
