The Silver Arrows having dominated the turbo hybrid era of Formula One for eight consecutive seasons failed in the development of the W13 under the new regulations of Formula One.
The Brackley-based team struggled in the early races as a result of the bouncing, which was a major hindrance to defending their Constructors’ championship title.
With only six races left to avoid having its first winless season since 2011, the team has yet to win a Grand Prix despite showing strong signs of recovery.
Horner claims he was surprised by the Brackley team’s sudden decline in performance.
Speaking on the Beyond the Grid podcast, Horner said: “Yes [I am surprised by Mercedes’ lack of pace].”
“Because they transitioned early [to the 2022 rules in ’21], they made quite a noise about compromising last year’s championship and moving over very early on to onto their 2022 car.
“Then, of course, when their car broke cover, particularly with this [zero sidepod] upgrade, it looks so radically different.
“You just have the expectation, from seeing how dominant Mercedes have been, that they would be in a very similar position.
“Obviously [they were] hurt last year getting beat [to the Drivers’ title by Max Verstappen] but we felt that they would come back with a renewed vengeance for this year.
“So, it is quite remarkable that after the domination that they’ve had for the last eight years, that they’re yet to win a Grand Prix in 2022 [prior to the Singapore Grand Prix].”