Former Waikato halfback Kevin Putt, who played for the Sharks in Super rugby, said the Chiefs had lacked match-winning direction at halfback and first five-eighths for some time, but they were more likely to get it from Leonard, who will start tonight, than Kerr-Barlow.
"Leonard in the past has been bloody good, but we haven't seen his best for a long time," is Putt's frank assessment.
"This [change in coaches] could be the resurrection of his career."
Kerr-Barlow is a product of the Hamilton Boys' High School talent machine and was highly regarded by Ian Foster, so much so that he was tipping higher honours for the 21-year-old, sooner rather than later.
"I'm not certain he's the calibre to claim a spot as one of the top five halfbacks in the country and therefore deserve a starting spot at a Super franchise," Putt says. "But on that basis, neither is Leonard on recent form, but he can reach that calibre, we've seen it before."
Where Leonard gets Putt's approval is he is easier to work a game plan around.
"Kerr-Barlow's inconsistent. When he's on, he's bloody outstanding but he reminds me a bit of Alby Mathewson - can be electrifying on the run but a bit headless with it.
"Technically he's not the perfect halfback."
Putt is quick to add that Leonard's technique had also slipped, but believes he could get back to the form he showed when he and Byron Kelleher were vying for top dog in the All Blacks in'07.
"He came on to the scene as an impact player off the bench, but by God he did some incredible things with his support play and his general marshalling and defensive work."
Both will get chances, no doubt, but one thing Putt would like to see the Chiefs abandon is the premeditated substituting of the halfbacks between the 45th and 65th minutes, popularised by Graham Henry and the All Blacks.
"Will you get greater impact with someone coming on fresh? Yes, potentially. But if you've got a man that's got total control of the game, why on Earth would you change them?
"I've got to be careful what I say here, but I think it's absolute bollocks.
"It was Graham Henry covering his arse because Piri Weepu was a brilliant rugby player, but had no aerobic capacity to play for 80 minutes.
"A young Kerr-Barlow? No. Leonard at his best? They can get through a full game with no problems whatsoever.
"I get immensely concerned when I see guys who are controlling the game - and I'm not talking about the Chiefs in particular here because they've lacked that command at halfback and No 10 in recent years - being substituted."
Having highlighted Leonard and Kerr-Barlow's shortcomings, Putt adds that both are capable of becoming better players - Leonard returning to peak form and Kerr-Barlow maturing - in a short space of time under Rennie. "I'm excited by where they're headed with the Chiefs. A shake-up is what they needed. A new broom sweeps clean."