He has indeed brought the team its sole podium of the season to date, starring in wet conditions at Sandown back in March.
But it's Will Brown who holds a top 10 championship position – one spot and six points ahead of his team-mate – having looked the more threatening of the Erebus duo through the rounds that preceded the lengthy mid-season break.
Kostecki by contrast has managed just one top 10 finish in his last seven starts, with qualifying pace having been a struggle.
“It was definitely really up and down,” the #99 Boost Mobile-backed driver told Speedcafe.com of his first half of the season.
“At the start of the year I said I want to be fighting for race wins by the end of the season.
“We've had good speed here or there but just the consistency hasn't really been there for the #99 side of the garage, so if we can sort out a few of those factors then I think we'll be in contention for that top five mark more often.”
On the post-Sandown run of results, Kostecki noted: “We had a bit of an average run at Tassie and we sort of went okay at Tailem Bend and we had a good run going on for Darwin and got taken out there on the last two laps.
“We've just had a few unfortunate things happen during races that have sort of taken us out of running in the top sort of seven or five mark.
“Really struggled the first week of Townsville. Both cars were pretty average at the start of the weekend and Will's side of the garage did a good job of exploring down a different path for the Sunday race at Townsville 1.
“We opted to go to that direction for Townsville 2 and both cars were sort of around the 10th mark. Just a few things we have to improve on our side of the garage but it will just be cool to go racing again.”
All in all, Kostecki said he hasn't been caught off-guard by Brown's ability to match up well.
“I haven't been surprised, Will is a good driver and we have been trying to push each other as much as possible,” he said.
“We both want the same thing, we both want to win, so we're just trying to push each other as far as we can.
“Pretty much most races this year we have qualified next to each other so we've mostly been dooring each other going into Turn 1 at most places, so that's been pretty cool to see.
“But at the same time, we just need to move both cars up the order.”