Warrington half Ewan Irwin was smart enough to exploit a disjointed defensive left edge struggling to adjust to the temporary loss of the experienced centre and created the score for Albert Hopoate.
Percival had been ushered off for a Head Injury Assessment, triggered by a gumshield alert, and although he was subsequently cleared to play on the damage had been done with Wire back in the game.
The alerts have become a talking point among players and coaches impacted by them since rugby league introduced instrumented mouthguard triggers this season.
Although they have been in use since 2022, they have stepped up this season with the real-time triggers alerting medical teams immediately when a player experiences a high force to the head.
When a trigger occurs, the mouthguard flashes red and the team’s medical staff are immediately notified, even when there are no immediate visible signs of injury.
Percival’s exit was untimely, not least because Saints had already shuffled their back line with Tristan Sailor moved off the wing to replace broken jaw victim Jonny Lomax.
When asked about the disruption caused by the alerts, Rowley responded: “We had two the previous week at Leeds but it’s not too bad when it’s a middle.
“When you’re already at sixes and sevens on your edges anyway and then you have to take a centre off it caused tremendous disruption.
“And it’s annoying because Percy obviously had not got a clue what’s going on at that point.
“His gumshield’s flashing, but it’s from an innocuous carry from two or three minutes earlier where there was no real big collision.
“It does feel like something of a lottery and I don’t know how they quantify the alarm bell going off.
“We’ve had several of these ‘gumshield triggers’ this year and so far none of them have come up with a failed HIA.
“It is just so disruptive, and I’m not sure we’ve got the right amount of exchanges personnel on the sidelines to support it because it can have a big disruption on teams and outcomes.”
The Saints boss understands that player welfare is a priority – and in recent years, given what we now know about head injuries, the game has to put measures in place.
However, he offered an alternative to the current system.
He said: “Maybe a good solution would be not having to wait the full 15-minutes under the protocol for the normal HIAs.
“So if it’s a flashing gum shield – and in Percy’s case where he’s ultimately confused as to why he’s coming off – then do the head test and if he’s cleared it in two to three minutes then get him back on.
“I support looking after players, but it was disruptive and very frustrating.
“It’s one of those things you’ve got to put up with because the game’s going through a process where they’re trying to look after the players and I’m a full supportive of that.”