The Chiefs were behind all match, won by the Stormers 36-34, and were second best in almost every facet, yet they almost won it.
It was an interesting concept for Rennie to come to terms with afterwards - being so competitive without firing a shot up front, while knowing they could have comfortably won had their forwards played better.
As it was, the Stormers, led by captain and Springboks lock Andries Bekker, completely outplayed the Chiefs in the lineouts, collisions and breakdown. It was an impressive performance from the men in blue and white and it resulted in their first victory of the season.
"Ultimately we have 12 points in the first three weeks," Rennie said of the Chiefs' start to the season. "I believe we'd have taken that at the start of the season. That amounts to three wins but it won't mean much if we don't deliver this weekend.
"We lost the collisions with and without the ball, we played a big chunk of the game without possession, they had a pretty aggressive lineout and stole a bit of ours and we gave away penalties and we almost won the game," Rennie said.
Ill discipline also cost them - they were without halfback Tawera Kerr-Barlow late in the first half due to a yellow card for constant team offending at the breakdown and replacement flanker Nick Crosswell late in the second for a silly obstruction as they chased the game.
At the end, first-five Aaron Cruden, who had a mixed game, had a chance for a dropped goal but ran it, only for the Stormers to win a disputed breakdown penalty from referee Jaco Peyper.
The decision to penalise the Chiefs when it appeared a Stormers player had left his feet in the ruck to claim the ball didn't impress Rennie, but the Chiefs coach conceded his side didn't deserve to win.
Cruden created tries for Charlie Ngatai and Tim Nanai-Williams with grubber kicks, a tactic to counter the Stormers' rush defence.
However, the All Blacks No10 also made errors - losing the ball in contact in front of his own posts which lead to Gio Aplon's second try, and dropping a pass cold when on attack in the second half.
Ngatai scored his second following good work by Nanai-Williams and Gareth Anscombe. Replacement midfielder Andrew Horrell, back from a foot injury, scored in the corner with 10 minutes left to set up the Chiefs' big finish.
Stormers 36 (Gio Aplon 2, Nic Groom tries; Joe Pietersen 3 cons, 5 pens) bt Chiefs 34 (Charlie Ngatai 2, Tim Nanai-Williams, Andrew Horrell tries; Gareth Anscombe 4 cons, 2 pens). HT: 26-17.
