Crusaders forwards coach Jason Ryan will join the team in Plumtree's place, while Foster himself will work with the backs in the short-term. Joe Schmidt will also be involved in the group, working with Foster when it comes to the side's overall strategy and attack play.
The side is set to gather in Wellington on Monday ahead of the start of the Rugby Championship and, with a little more than a year to go until the Rugby World Cup, Foster said he believed the team were not far off being in a position to be a contender for the title.
However, he admitted they needed to put their foot down and make the progress he believes they are capable of in their opportunities before then.
"We're connecting the dots. We've got to do it quicker," Foster admitted.
"There are a couple of Achilles heels in our game that we dealt with well in the Irish series but they came to bite us in that third test. We've got to sort those things out and if we can – and I have utter belief in the direction this group is going. But we have the Rugby Championship; we've got to hoe into our work, we've got to get away from feeling oppressed by all the tension that's out there and we understand that people are frustrated but at the end of the day that doesn't help us. We need clear heads, a desire to go and play, and fundamentally start doing the things we know we're good at."
Their first opportunity to do so comes when they travel to South Africa to begin their Rugby Championship campaign in a two-test tilt with the Springboks, with the first test at Mbombela Stadium on August 7, before a visit to Ellis Park the following week.
"It's not the first time we've been slow starters in July. I hate saying that, but it is reality," Foster said. "We've got to speed up the gains we want. We're a wounded All Blacks team. We've got a job to do over there and we actually want to play a game New Zealanders are proud of."