It was one thing for Wales to struggle with the Chiefs' running game - many Super Rugby sides know that feeling, although that component is usually marshalled by Aaron Cruden and Damian McKenzie. But it was quite another for the tourists to be so ineffective when they had their hands on the ball.
"It was disappointing," Gatland said. "[The Chiefs] defended well and, when the chances came their way, they were excellent. The dominated us at collision time and sometimes the game of rugby is very simple - it's a physical game about collisions."
The Chiefs' supremacy in that area was especially clear in a first half that was equally about the home side's defence and the visitors' profligacy. In an ultimately unsuccessful search for fluency, Wales were aimless in the opposition 22 and toothless when close to the line, repelled by a fierce opposition but too often picking the wrong option at the worst moment.
And when they hit the Chiefs' line they were hit hard, unable to match the home side's physicality at either end of the field. Being forced to survive with less possession and worse field position, the hosts were almost unstoppable when they sniffed a chance, with Donald's strength setting up Brad Weber for the opening try and setting the tone for what was to follow.
The Welsh defence wilted when faced with sustained pressure close to their own line and their solution - to soak up as much possession as possible - was only so effective. Another prolonged stretch deep in opposition territory would come to nothing and another lightning-fast Chiefs break would provide a clinical lesson in what Wales were lacking.
As on Saturday night, Gatland's men were a distant second in the final quarter, as a Chiefs team short on match fitness blew out the score with a couple of long-range raids, allowing the crowd to complete a memorable night with a well-deserved standing ovation as the cramping Donald limped from the field.
"It was a pretty special performance," said coach Dave Rennie. "I think our leadership group, led by Beaver, did a really good job of creating a hell of a lot of excitement. There was an opportunity to get an international scalp and we knew it was going to be watched by massive numbers around the world. So we're just really proud."
Chiefs 40 (Weber, Sanders, Bird, Donald, Pulu, McNicol tries; Donald 4 cons, Lowe con)
Wales 7 (Dacey try; Priestland con)
Halftime 21-0