They then staged a great second-half comeback at Cooks Gardens against Wairarapa Bush B, winning 32-29 after being down 29-10 going into the wind.
The roll continued with a 50-8 away victory last weekend against Wellington Maori Colts to secure a spot in the final.
The team usually don't know the line-up until Thursday afternoon, after the Heartland squad is decided, and even then some players may be unavailable.
However, Ratima said he and assistant Cornel Mason had worked hard to establish relationships which also meant guys like No 8 Jack Hodges, reserve back Liam Richardson and reserve forward Cole Paki had been able to slot in quickly after joining late.
Players like reserve prop Lucas Puts, flanker Faalafi Vave and lock Simon Hillis have also been in and out of the Heartland team and did well at that level.
"We were under no illusions [constant changes] would be the case coming into that coaching role," said Ratima.
"It's been good having lots of those players to call on. People want to play with the Development team, rather than see it as a cop-out after club rugby."
A family funeral means hooker Junior Tume will be a big loss for today's game, as is Robert Lavin joining the Heartland squad. The team has brought in Ratana's Hawea Meihana to fill the role.
A welcome return is "class player" Bradley Graham in his comeback match after being knocked out against Horowhenua-Kapiti on August 24.
Kickoff in Levin is at 12.30pm.