With Stephen Perofeta off to the NZ Schools development camp, Caskey was counting himself lucky he can call on a player with Koro's ability and experience to fill the role.
"We know exactly what he's going to bring to the table."
The recall is among a handful of cosmetic changes to the backline from the side that demolished North Otago last weekend.
Ace Malo comes back into the starting XV at fullback, with import Trinity Spooner-Neera moving into second five and Troy Brown going back to the bench.
While Malo is a proven commodity, Caskey said the utility back still has had only 35 minutes on the pitch so far and needs conditioning after recovering from injury.
"We want to give Ace more game time and get him back to fitness.
"You can't buy [experience] but you also have to have game time to be at their best at the business end.
"Also, it gives Trinity a chance to get the ball in his hands."
Kane Tamou again swaps with William Short for the reserve halfback role with the assignment to probe around the fringes of the tiring Buller forwards late in the game.
The pack remains basically the same, although the dreaded lurgi has been doing the rounds, as lock Sam Madams was a late switch into the starting lineup for an unwell Fraser Hammond down in Oamaru and the two were bracketed again ahead of last night's training.
"There's a couple that are sick " Ranato [Tikoilosomone] is as crook as a dog so that may be a change as well," said Caskey.
After an unbeaten 2014, right up until meeting Mid Canterbury in the Meads Cup final, Buller have struggled out of the gate this year.
They came from behind to beat King Country 32-20, then lost to neighbours West Coast 21-7 and were beaten by a converted try in injury time by Wairarapa-Bush 14-13 last Saturday.
Caskey points to the move to Nelson by James Lash " who he rates as Heartland's best first five " as the primary factor for the slump.
"Lose that and it's going to take a lot to get over and asking more of the players around."
The small union has still brought in a handful of loan players, and like Wanganui they can call on key veterans in prop Logan Mundy (87 games), lock Craig Moore (46), halfback Andrew Stephens (73) and mid-field back Penijamini Nabaivalu (65).
But none can match the services of flanker Luke Brownlee, 35, with a national record of 145 consecutive NPC matches out of his 170 provincial caps, while prop Phil Beveridge, 41, has clocked up 150 appearances.
"I don't think you'll ever see that again in New Zealand rugby. You wouldn't even dream of it," said Caskey.
Five of Wanganui's current team know the pair very well, as there is the small matter of their payback from losing to Buller twice during the horror 2013 season.
Kickoff is at 2.30pm tomorrow, following the 12.30pm curtain-raiser between Wanganui Under-18 and Wellington U18.
