"My basic measure is how their times stack up with what they did earlier in the year," he said today.
"If they can show some level of improvement.
"They're in different levels. Some are going to their first big international meet; others have been to Olympics or world championships before."
Lyles, who enjoyed considerable success with the dominant Shanghai club, and had a hand in the last two Olympic cycles and the medals won at them, knows he needs plenty more time to get a strong working relationship in place.
And he made it clear he's keen for a long stint.
''I've been in all my previous jobs for seven to nine years. I'm not a guy who likes to move around and I want to make something of this group, and this country," he said.
To the extent that he talks of, not only Rio in 2016, but beyond.
"I don't know these guys very well. We've spent a lot of time together in the pool and away from it. I've really tried to get to know them. They're a good group of guys but for me this is a first step along a long road to the 2016 Olympics, and hopefully 2020 (Olympics) as well," he said.
Freestyler Matt Stanley, keen to make amends for what he regards as mistake-laden meets in the London Olympics and the world short course champs in Istanbul last December, is impressed with Lyles.
"There's been a lot of changes since the start of the year, lots of different coaches with different input," he said. "It's great to have David here, so we have a concrete structure and leadership around the team. I've really enjoyed his training and I think I've already made some nice gains."
The New Zealand squad fly to Barcelona on Saturday and have a seven-week buildup before the worlds begin on July 20.
New Zealand team for the world champs in Barcelona, July 20-August 5:
Pool: Sophia Batchelor (AquaGym, Christchurch), Lauren Boyle, Shaun Burnett, Glenn Snyders, Mitchell Donaldson (all North Shore), Nathan Capp (Greerton, Tauranga), Gareth Kean, Samantha Lee, Samantha Lucie-Smith (all Capital), Matthew Stanley (Matamata).
Open water: Cara Baker (Howick Pakuranga, Counties Manukau), Emma Robinson (Capital), Philip Ryan (Waterhole, Auckland), Kane Radford (Rotorua Aquatics).