Two big wins over the Crusaders aside, the Chiefs' six other victories this season have been by 10 points or fewer. So while they are enjoying their first four-match winning streak since 2013, the year of their last championship, forgive Rennie for curbing his enthusiasm.
"To be honest, we were pretty grumpy after the game," the coach said. "We got five points and I guess we'll be happy with that, eventually, but the quality of the performance wasn't good enough.
"We really wanted a foot-on-the-throat attitude in that last 30, and we got ourselves in a position to score a lot of points but didn't do it, didn't finish and were too inaccurate or too loose. It's disappointing but we had some fairly young fellas out there and they would have learned a fair bit."
It was an inexperienced group who leaked the late tries. Already missing the injured Aaron Cruden and the rested Liam Messam, substitutions saw Brodie Retallick, Sam Cane and Hika Elliot all spend the final stages on the sidelines.
That trio had been part of a forward pack that dominated the scrum to such an extent it was almost cruel on the Force, who had to withdraw flanker Angus Cottrell when halfback Ian Prior was dismissed for a tip tackle on Tim Nanai-Williams in the first half. The set piece at least provided some reason for encouragement, continuing to shine after an impressive outing in last week's crushing of the Crusaders.
"Our scrum's gone pretty well all year," Rennie said. "Obviously they lost a man and had to throw a back into the scrum, so they battled with that, but I think we were dominant from the first scrum. We got penalised for a couple that I'm not really sure about but certainly the scrum was excellent."
But their competition-leading defence was found lacking, doing much to darken Rennie's mood. Too many tackles were missed and, after coming into the game having conceded eight tries in nine matches, the Chiefs shipped four to a last-placed side.
Improvements must be made ahead of Saturday's trip to Melbourne, where the Chiefs will encounter another lowly team. But the Rebels have provided glimpses of their danger and, with a long-awaited showdown with the Hurricanes looming, Rennie was wary of letting standards slip.
"[The Rebels] are a pretty good side," he said. "They knocked over the Brumbies last week and knocked over the Crusaders in Christchurch. They've been there or there abouts a lot of times, so we're conscious of that."
